welcome, charlotte! while i am sorry for the recent loss of your husband, the fact that searching for help to camp and travel on your own has brought you to us here on this forum is a good thing.
everyone here is most helpful and kind. did you have the uhaul
sent from the mainland or did you buy it there? it's very exciting to get started with a new-to-you camper. so it needs some tlc---that's something you will work on as you can.
the bunkbed issue---we also needed bunks, but only temporarily, a few years ago. what we did
was to build the frame to support the upper bunk from wood and made it able to sit onto the bottom bench. it was screwed into the upper bracket for support as well. it worked like a charm and when we didn't need it, it completely disassembled and was storable in the garage.
perhaps someone you know who is handy with wood could help you come up with something similar.
i also know someone who puts her 2 grandkids to sleep on the "big" bed and she sleeps on the single bench, eliminating the need for bunks.