First of all, enjoyable stories!
45-50', full of air... That's 4000-6000 pounds of air, ouch if sweet love rolls on you.
I'd suggest filling them with hydrogen, the lightest gas ever, then they'll weight merely 300-400 pounds and will push the ceiling up with the difference between these two weights. If they get outside, then sex will take place on the altitude 15 miles where temperature is -48 F. Take warm clothes! ^_^
I guess I'm just choosing comfortable position ^_^ it's just a strange thought inspired by Luther's Buoyancy. Your stories are wonderful as they are.
Hannah because bigger is better
I might be a bit chubby now, but, ya see that hose over there?
You know what to do with it~