When I built my 30x50 I asked for no end walls. I then had a friend who did metal studs come and build them to my exact specs. I too went with two roll ups and find it very useful. I did consider one long roll up but my friends in construction talked me into the two.
I do wish I had gone with a taller roll up for the left one just to be able to work on a small travel trailer we later got that is to tall to get in.