most male turtles would be fine... dont get a female if you dont want it to be crampped in the tank! the " 1 inch of turtle needs 10galls" is not neccicarily true, its just to help you understand the range of your turtle tank... i 90 gallon tank would be goos for a 1ft turtle
eastern snake neck turtle... they get 11 inches and are very good looking. IDK how much they cost or if they even have them near you but they are awesome
I would also say eastern snake neck (Chelodina mccordi), roti island snake neck (C. mccordi) or New Guinean snake neck (C. novaguineae). A cheap alternative would be Mesoclemmys gibba.
Pink bellied sidenecks need big tanks as well. Females get well over 10 inch and tend to be really massive, while snake necks stay a little flatter and thus lighter.
You are definitely right that the common snake necks like Macrochelodina rugosa get fairly big, but the smaller ones from the novaguineae-group are easy to keep in a 90 gal tank.