Funny thing is I've actually done this. It was for a local adult art class taught at the museum and they kept a logbook of about 50 models for the class.
You got paid $25 an hour non nude and $40 an hour nude (this was 1995 money) DUH so guess which one I picked? The embarrassment part was over in about 5 minutes and the rest of time you fought off dozing because that would irritated the hell out of the instructor.
Anyway I only saw maybe 3 other models because of the schedule and only one of them was female, and TRUST me you did not want to sit there and draw those 50 year old folds for hours on end