[Thin Lizzy]

You can change this but go slowly, having a door in the front does makes it less frightening when they see your hands, I always go for a cage with a top door and side door. It may be that instead of putting your hands in, use a tube or box for Jaska to climb into and then transport him to a play area, but start of with a small play area using some of his cage toys. This will help him build confidence slowly.
Also I would suggest the toilet paper trick, stuff some up your sleeves and leave for a couple of hours then place in his cage, he'll be curious and sniff it, this lets him get use to your smell, do this daily add a little for a week and see how he reacts to you then.
Mine have always pouched the toilet paper to use as extra bedding. Make sure it's unscented.
If the small play area works then gradually increase the size.