Auxiliary fuel tank users -in bed variety

Any issues?
My understanding is you put it in, plumb it and only fill the aux tank right?
I thought it was straight forward till I read some reviews on Northern Tool for the connector kit.
There were a few talking about fuel seeping out around the neck over flow etc.
Some said that the ball valve in the connector kit stuck and caused leaks.
Anything to this?
I assumed you hooked it up and only used the valve if you had to open your fuel cap for some reason.
Please enlighten me. I have a trip planned the week after Labor Day and I am thinking about putting one in.