For me, a transcon without lav availability would pretty much be a no-go (so to speak). 10 years ago, no issue. Nowadays, maybe three hours would be the limit for comfort, and if you then factor in the possibility of turbulence when the facilities might finally be available (the 2 out of 8 or whatever)... it just wouldn't be my idea of a fun time.

It amazes me that the FAA doesn't have some minimal requirement for lavs.