Maybe you could set them up in the bathroom at night. One very important piece of advice....Never Ever keep a kitten or cat anywhere without access to a litter box! I don't mean to sound harsh but you will be setting yourself up for big trouble if you do that. They can not hold their tiny bladders and once they start using potty in inappropriate places it's very hard to break. If they attempt to hold their bladders for too long they can develop urinary problems too. If you give them access to your room all day but keep them in the bathroom at night all should be ok. Just make sure that there is a litter box available at all times.

Godo Luck!