We bought our first trailer for a two month trip planning to sell it at the end of the trip. The bed was 4 feet wide, like a large twin. We joked about learning synchronized rolling over.
It turned out the bed was plenty wide. We liked it so much we sold our motorhome with it's queen sized, walk-around bed and have been in a small trailer for the last 6 years, spending well above 1,500 nights in small trailer beds.
We're both now 71 and actually like the coziness of our bed. I'm 6"1' and 185. Of course we have no pets believing in "no pets, more petting"; maybe that's part of the reason we like our bed, too old to find someone in a king size bed... it's funny when we're home even our queen seems too big, actually our house seem too big as well.
Ginny and I treat RVing as though we were 16, kids exploring the world. Recently we had newly weds at our home. They refused to take our bedroom that we give to all our guests and instead took the 'kid's room' which has twin beds. They used just one of the twins.
In our first trailer I slept on the inside and was in the crawl over mode, actually easy for the taller partner and minimally offers the opportunity for a passing "I love you". In our present trailer I sleep on the outside and just get up when Ginny wants to use the bathroom.
As to Donna's comment about trailer height it does turn out to not be critical. We borrowed a 5'10" Casita
16 for a year and surprisingly to me we did just fine. Donna's right, one rarely stands up and second nature keeps you from hitting the ceiling. However when it came to buying our own fiberglass trailer, we did buy the taller Scamp
Now this is our take. We know for many pets are critical to their life, that some need space.