I really didn't find the tank build so terrible. If that was the only reason to buy the quick build wings, I would suggest biting the bullet and building them.
Go slow. Have several rolls of paper towels handy, clean the gun and each cleco as you use them. Have a box of disposable gloves handy and change them each time you get messy.
For mixing the Proseal, I use a pad of paper. Mix the Proseal on the top sheet, then toss it or set it aside (to check curing later) and you have a clean sheet to mix your next batch. I have a box of tongue depressors for mixing and spreading sticks.
One other comment, after testing the tanks using the balloon method, I used air and a little (very little) more air to lightly pressurize the tank. (Using the tank pick up and a valve to add air, with the vent sealed and the cap in place, until a slight bulge of the skin appears ) With soap bubbles I found a leak at the corner of the rear bulkhead that did not leak with the balloon test. After fixing that I purchased 2 gallons of AV Gas and put it in each tank sequentially and sloshed around, to ?test? and to clean out any debris. I found that sealing the vent and fuel pick up, the tank would develop an internal vapor pressure from the gas (similar to the air test I did) confirming a good seal.
This might give a high level of confidence that the fast build tanks are well sealed.