I used the Van's leak test kit and created a little connector for the balloon off of the return line.
Pumped the tank up slowly until I had some pressure in the tank and once the balloon inflated, I stopped the pumping of the bicycle pump. The balloon is basically a safety valve in case there is to much pressure.
Sprayed the entire area with a soapy water solution and watched very closely. The only area creating bubbles was the joint where the balloon was attached.
I'll call this a success and claim to have leak free left fuel tank!
I'll prime the baffle area and the inboard and outboard ribs later on.
In picture #2, you can see my sod all churned up...re-sodding. Like I don't have enough to do already.