Are you sure you are not confusing with Multi Entry Non O? There is no proof of funds for tourist visa (unless extremely frequent). I did a single entry Non O in Savannakhet 3 weeks ago and had to show almost nothing, and nobody that day had bank statement for their tourist visa.
You mean the yearly extension that you need to report every 90 days. But you can report online, it take 5 min, no need to drive anywhere except on your first report (any 2nd, 3nd, etc, can do online).
I'm currently on 90 days single entry Non O and can extend 60 days once. Before, I was on visa exempt and extended once for 30 days and a 2nd time for 60 days. The reason why you can do both on visa exempt or tourist visa is that you first extend for tourism reason but than extend again for a different reason (marriage). But when you enter on Non O you are already on a marriage visa so can only extend for that specific reason.