Is there a "best vehicle" for HHO mod.

I have been experimenting with my 2000 Astro van with mixed results. The problem I am having is that this van is full of sensors. MAP, MAF, and three O2 sensors in the exhaust. Instead of wasting my time trying to fool the ECM on this van I have a better idea. I'm going to buy a cheap, used car with a small engine for the purpose of hho tests only. What would be a good vehicle for this application. What kind of cars have the least amount of sensors on them. I don't want to buy a car thats so old I'll have to do excess repairs just to make it road worthy. I'm thinking something like an older toyota corolla or geo metro, but they're probably full of sensors too. Any ideas would be great, Thanks.