It's completely doable, but I can't really say how hard it would be as that depends greatly on individual ability and patience. It would certainly be more involved and complicated to design and build compared to not having the dock function, but it's a perfectly doable project and has been done successfully before. You'd be hard pressed to make a portable as flat as the switch, you'd be looking at a case around an inch thick at least for a first timer, but all the functionality you described is possible to do. Personally I wouldn't call it so much hard as I would fiddly and time consuming. The principles behind it are relatively simple, but may take you some time to understand and implement depending on how familiar you are with electronics and how quickly you learn.
Either way, you have access to a significant trove of data here from past build logs and there's a lot of support available from the people here. You can ask as many questions as you need to