Instead of that strap, just make sure your bow is tight to the roller with the winch strap.
Then setup another cable or chain with a clip as a hard mounted 2nd tie down. This one would just be an aux tie down, and doesn't' need to be tight.
Do you have rear tie town straps? I highly recommend the boat buckle tie downs.
Yep, they're more expensive....but they are ALWAYS there when you need them. Everyone i know has lost a strap or 2 off the back, and you never need to replace these ones.
http://www.dhmtrailers.com/online/pr...&cat=78&page=1