There is another option out there and that is a dual hitch extension. I also have the undercover and I am not too keen on drilling holes in it. I have used the dual hitch for my bike rack and towing our travel trailer at the same time. One catch is that it will reduce overall towing capacity by some percentage but if you are just looking to tow bass boat and carry some bikes with your F150 that should be no problem.

Here's a link to one: http://www.northerntool.com/webapp/w...92929&R=492929

 

The UnderCover is strong enough, I believe, but I would not do it. Go to my gallery and see the underside of the UnderCover. It has molded braces for strength.