I've been away from this thread for a few days, and in that time, it seems like you've been given some great advice and rejected all of it. However, I've done this two zillion times here too (v-drive ballast, accuski vs. perfect pass, etc., etc.).
Each and every time, Pete or some other dude that knows a lot more about 1) these boats, 2) boating, and 3) boarding than I do throw down with advice that I question or outright reject.
There's something to be said for thinking for yourself, and also about the benefits of learning from others/not reinventing the wheel. I for one am a little hard-headed when it comes to rejecting ideas that make sense to me because someone who knows better rejects it. I'm sure most of the time they're right, but so many times people just rely on assumptions, "everybody knows that boat engines are under way more load than car engines", or fail in the execution, only call the idea bad.
My two cents: try to borrow some sacks from friends or people in the area just to try things out and experiment with different things. It's really kinda foolish (I speak from experience here) to plan a ballast system without having tried a whole bunch of different stuff with some experienced dudes IN THE BOAT to point things out to you. During that recent run of mine, I'd have assumed the hole shot was too slow and would've backed off if it weren't for the guys with me who regularly run pro wakes in other boats. If you insist on buying new bags, get custom rectangulars made to fit.
My two cents.
Lesman, there's only one pump thou shalt use: the official pump of epicmarine.com, the Rule 1100. Sold in many forms, but my for was as the Bump Pump. Use nice big tubing and you'll just be amazed at how much water these rules pump. I'll use them FOR SURE when I do my auto-ballast (that is unless someboday comes out with a reversible vane pump that moves more than 80 pounds a minute while burning 20 amps.)