I also would recommend having your shelf sitting on the base to instead of attaching to the bars as in the Detolf the bars are vertical and the shelf might not securely attach to them and possibly slide down with the weight of toys etc.
Having the shelf standing on the floor the shelf will be more stable but this doesn’t mean the shelf can’t be to the height you want - as you would fix wooden dowels to the shelf and they will be the legs to the shelf and you would also be able to have a ramp leading up to.
I use a Knuff shelf in my DIY cage which stands on the bae of the cage. But with the legs the shelf stands half way up the cage and I use a bendy bridge from Pumpkin’s house roof to the shelf. Here is a link to a post in my hamster’s thread were I have posted pictures of my shelf -
http://www.hamstercentral.com/commun...5-post162.html.