When we redid the two gaucho beds in our
amerigo, we cut the front bed/settee from 40" extended, down to 28." 8] It is a good depth for a little daybed with a foam bolster at the back, and Paul sleeps fine on it at night as he is a sound, quiet sleeper. =^} The back bed used to use the typical table/two bench arrangement and would make into a 50" bed (not quite a 54" double) and we cut that back to 32" so as to have two 18" wide seats making a U-seating arrangement (using a small, portable folding table) as well as a permanent "twin" bed. It's wide enough for me. The front bed/settee is about 73" long (just long enough for Paul at 5'9" and the back is closer to 77" which is long enough for me plus a pug at the foot. (We cut up a queen mattress to make the back foam plus the side seats, so we had more length to use--the trailer is 77" wide at that point). Both of ours use half of a "found" metal futon frame underneath. Since our foam is 7" thick, we use the futon frame just as it was, so there's lots of airflow. 8-)
Agree with Tap, above, I wouldn't go narrower than 28" with 30" being better. 24" width in some side seat/beds really is awfully narrow for an adult, and is impossible for me, being horizontally gifted. ;-D