You do need to be careful with sand, there are various different types (mineral) I think. Moving his potty to a convenient place won't help unfortunately. The potty has to go where they choose to wee! Tried it myself, after Charlie was potty trained - moving his potty to where I wanted him to wee - they just carry on weeing in the same place whether the potty is there or not!
I should put it back in his wee corner with substrate for now. There are all kinds of things you can use in a potty. Chinchilla bathing sand is one, and what most people seem to use - it does seem to soak the wee up well and help reduce the smell. Finacard also sell some kind of cardboard litter for a litter tray (they do the cardboard substrate, paper bedding and nugget type cardboard for potties - although I haven't tried it). I found Chinchilla bathing sand works out cheaper than hamster potty litter and the sand is safer as well. If they eat the potty litter it's not good for them.
If you remove the shelf your hamster might move his potty corner! But then it might be somewhere more inconvenient (tried that too lol). I would suggest either managing where it is (you only need to clean it out every 4 or 5 days really), or another alternative is a large house. Whenever I have given Charlie a large house he has immediately moved his wee corner inside the house - luckily the potty tray fitted in one end of it, but I ended up buying him an even bigger house so he has room for his hoards, nest and potty in there. The house has a lift-off roof so it's really easy to clean the potty out - I just take the roof off and lift it out. Because the door of the house is on the right (ie nearest the front of the cage) they tend to nest furthest away from the door, so the potty corner is the opposite end (ie nearest the door) - this is assuming the house is on the right hand side of the cage. If it was on the left hand side of the cage the door, and potty corner, would be at the back of the cage.
Most of the German hamster houses are quite large with two or three rooms, with one big enough to fit a potty in and it does seem that in a large house, they will do everything in there - ie do their toiletting in private! It means the house needs plastikoting on the inside though just in case it sprays - mine isn't plastikoted and is still dry and clean but Charlie doesn't spray lol. He's very neat in his house
This is the house I have now - it's actually classed as a Rabbit house but it's far too small for a rabbit. It just about fills the width of the cage with a couple of inches gap at the back behind the side of it (I have it as near the front side as possible for ease of access). It's quite tall, which is good, because it can stand directly on the base of the cage (I put the substrate inside it - a couple of inches - and pile it up round the outside to the same level as the rest of the cage) and then the roof level is about a couple of inches higher than the top of the cage base. So it makes a nice platform and it's easy to spot clean inside and empty the potty. This would make the platform quite a bit lower than the shelf in the Alaska though, so it might be quite a drop from the top of the cage to the platform. Leaving the shelf over it would make it harder to access inside the house. You could put a piece of hemp mat on the roof though which would make it a softer landing if he did fall on it. The height was right in my old cage which was much lower than the Alaska. My current cage is about the same height as the Alaska and I raised the house instead, by standing it on something, but putting a hemp mat on top might be easier. The Rodipet labyrinth house for Syrians is similar and really nice, but more expensive and quite a lot bigger - it would take up too much space in an 80cm cage I think. Anyway this is the house - it comes flat pack and the pieces just slot together like a jigsaw, so no nails. The plus side is - they seem to like a nice big dark nesting box and having their wee corner inside it. The downside is - it takes up some of the floor space (it sticks forwards about 25cm) and you can't put the shelf on the other side and still fit the wheel in I think. Unless you had a narrower shelf.
Anyway this is the house. the door is quite large so I put a tunnel over the front of it.
Ferplast 84646099 Wooden House for Rabbits SIN 4646 Total Size Approx. 34.5 x 24 x 16.5 cm: Amazon.co.uk: Pet Supplies
Our hamster has often shunned various houses provided, but not the large ones - he goes straight down the tunnel and makes a nest inside (the tunnel seems to attract them in because it makes it dark inside). If you had a large wheel on the back wall of the cage, next to the house, then you could fit a 20cm deep shelf on the left hand wall, which would increase roaming space, but that would mean buying a new shelf. Although I do have a 15cm shelf you could have if you want. It's only 46cm wide so wouldn't go the full depth of the cage and you'd need something to block the gap at the end. It came in my pack of shelves when I was setting Charlie's cage up and I used the shorter one as the longer one was too long for where I wanted it.
If you were going to adjust the set up though, it might be better to wait till he is a bit more tame first, so meanwhile I would just leave the litter tray where he pees
On the other hand, cage changes can set back taming, so there's an argument for doing it now and then doing taming.
This is the Finacard potty litter - it's for hamsters as well as cats. It costs £11.50 for 15 litres. 15 litres is quite a lot! The Chinchilla bathing sand is £4.31 for 1.5 litres, as a comparison.
Papelit Cat Litter : Recycled 100% Paper Cat Litter 30 litres for £9.50
This is the Chinchilla bathing sand - one of those tends to last me a month to 6 weeks.
https://www.viovet.co.uk/Supreme_Sci...g+sand&sct_r=1
Or you could just keep using substrate in it! I'm guessing it needs cleaning out more often with the substrate in as it probably soaks through more.