My two had their own "room" to sleep in but a situation happened where I had to let them sleep in my room. Magnus is a big boy so he has no problem jumping on/off my bed but Zoey being so tiny, couldn't. I purchased steps for her but she wouldn't use them. So I built a ramp. She caught onto that in no time!
After I moved, I set the box/mattress onto the floor but I still put the ramp next to the bed. I don't want her wearing out her joints. Even though she's able to jump on/off the bed at that height, she uses the ramp so I'm happy.
I also have pee pad in the bathroom and water for them in case they need to use it in the middle of the night. Magnus would get a drink of water sometimes but will wait to pee till morning. Zoey, she seems to use the pad few times a week. I know she's not able to hold it like Magnus.