I have ran the tt40's behind offshore boards most of the summer as well. I have no problem with the flag still working. Just have to make a few adjustments as Ben has stated. The newer tattle flag kits work better because they have higher pre drilled holes in the flag already which really tightens up the spring, but you can make the older flags work as well. I have ran 5 boards per side with the tt40's and have had no issues. The only time there is an issue is when the waves are 4' then the flags can catch your other lines, you have to spread them out a bit more with big waves. I ran spoons, spoon harnesses, double willow blade harnesses and shallow diving body baits behind them all with success.