The shorter and lighter you go, the harder it becomes to find a bus with anything other than the AT545 (or at least that is what I have observed in my limited experience). Plenty of people complain about the AT545 but plenty more people own and tolerate them. Avoid if you can but if you want a shorter bus, maybe don't consider it a dealbreaker. At ~30ft, I'll bet you can find a suitable bus with something else though if you are patient.
There is
a 31ft rear engine Thomas with I think a MD3060 and Cat C7 for sale by Las Vegas Bus Sales. 2006 I believe.
There is also a
TC1000 for sale in I think phoenix (I'm sure it has an AT545) that looks to be in good condition. Has A/C, high ceiling, 9 window (so roughly 26-29 feet I think).
I like the TC2000 and have never heard anything particularly negative about it.