Wish I could help you out, but I'm having fan problems too! Some of my equipment arrived today and when I tried out the 4" axial fans they were waaaay louder than I had expected. Totally fine if stealth isn't an issue, as I picked them up pretty cheap (25$ each). Definitely going to stick around and see what others have to say!
I've been on the fence between vertical bulb and getting a hood and going traditional horizontal style, the problem is finding one that fits inside my 23 7/8" x 23 7/8" footprint comfortably. I figured I could always try vertical first and save the 100+ dollars.
PS: If stealth isn't an issue, I'd recommend an axial fan or two as they are pretty cheap and while they don't move tons of air (my 4" axials are only rated 80CFM) like a blower, I think it'd be fine considering the confined space inside the cab.
Its always fun getting your equipment! Its like christmas.... except better
Stealth is a major issue with me, which is why I chose to get the S&P for my exhaust fan, so I don't think I would be able to get away with one of those fans.
Take a look at the hood I have, The original Super Sun. http://www.greners.com/super-sun-reflector.html It has a very small footprint, and the duct comes out the front and the back allowing it to fit in a much tighter footprint. The ducting is also 4 inch which is perfect for a small tent.