Hey, I'm a programmer by trade with automotive knowledge too, cool!
Wetcell tech is an awesome idea. My only worry is to make sure you do it before injecting any gas incase of sparks or discharge. The other thing is that passing the gas through a bubbler is supposed to add some help because you're adding water vapor.
I'm interested in trying HHO too, but I think the first thing for me to try is a PVC catch can and then pass that through a bubbler. I've seen some that really use up the water which means it's in the intake which mean a bit more efficiency due to steam expansion.
Here is the BEST resource I've found:
http://www.free-energy-info.co.uk/Chapter10.pdf
It goes through EVERY HHO generator you've probably ever heard mentioned as well as how to build your own EFIE. It has multiple construction plans for many devices and explains who a lot of the big names in the technology are. Also, EFIE is another very big component. Most newer cars will see the cleaner burning (less O2 content in the exhaust due to using it for lex COx and NOx and more CO2 N2) and add gas to compensate. The EFIE tricks your O2 signal to run at a leaner target. It's not super sofisticated but supposed it's the only way to truly see the gains with HHO.
Lastly, I have to agree with the others. Your 'fill up' every 3-4 days has to be really close to $100 each time. I'm not sure about your location but you should be able to find fairly reliable transportation for $1000 or less, probably even $500. There are plenty around me for $500 (sometimes even 2000 or newer Hyundais!) and if you throw and oil change and tune up they'll be bullet proof. If you find a $500 car that can get you 32MPG then it just has to last 30-40 work days to pay for itself! (Because $100/3-4 days * 10 = $1000/30-40 days and at 32MPG it's only $500/30-40 days and voila paid for!). Plus you always have your other vehicle as a backup (I'd want a back up for that anyway at 300k miles) and you can still spend a couple hundred and try HHO on your car and shoot for 50MPG plus saving you even more. Personally I'd experiment on the truck or whatever is not my only vehicle first and if it works move it to the car.