How do I make a 60 x 60 lot on the Sims 3 in town editor?

The reason is because the lot placement choices jumps from 50 x50 to 64 x 64 and that's barely too big for where I'm going to put the lot at No cheats. No mods. Also, I don't want to use a pre-made lot, by the way, this is in Bridgeport. I also need help locating a good place for a 60 x 60, since Bridgeport is crowded and has a lot of unrouteable terrain. I also don't want to evict the Big Bling household.