Easy twin sheet modification
First of all, this idea is not original to us. We read a post here that gave us the general description and we modified it to suit us. We would give credit to the original poster but haven't been able to find the post again.
This idea will only work if you are using some kind of foam mattress topper. We purchased 2 flat sheets (full size) to be used in place of the fitted ones and attached iron on Velcro in several places along both long sides of each sheet. To change the bottom sheet, remove the topper and lay the sheet on top of the mattress (Velcro side against the wall) with the excess sheet pooling on the floor. Place the topper back on the mattress/sheet and pull the excess sheet back across the mattress, hooking the Velcro. That's it, no more wrestling the mattress to get the fitted sheet in place.