Hi Melaik!
I did this once. When I have to be away for holidays I take my Chito to a boarding place, but due to space reasons he’s not able to get his daily exercise. I feel really bad about leaving him for long, but there’s nothing else I can do
That being said, when I get him home, his tummy would usually be a little sad, so I have to proceed with a hay-intense diet for a week or so before reverting back to also giving him a bit of pellets and veggies so his tum would return to normal first. I suggest giving your bun some Bene-bac before you go just in case the lack of exercise or incorrect diet (if he has a lot of treats bc everybody is a sucker to those big, begging eyes) stresses him out, then a ‘detox’ when you’re back home.
As for the method of getting him in and out of the bathroom, I agree a carrier would be best. But if you don’t have one, a box would do until you have one
The main thing is for your brother to not stress him out while loading/unloading him in and out, bc Chito gets upset about that :”)
Good luck!!