Except for the first of four boats, we have had surge brakes on our boats that we pull behind our FW and have never had a braking problem. I think it would be very hard to rig up electric brakes on the boat trailer rather than surge brakes. Even backing up, with the boat attached, as long as you have the trailer plugged in as the surge brakes are "de-activated" when in reverse if the trailer lights are plugged in, I think. Unless there are no back-up lights on the FW, then that could be a problem. However, as I have never backed up the FW and boat at the same time, I might be all wet.
2012 GMC 2500HD D/A Crewcab
2012 Jayco Eagle SuperLite HT 26.5 RLS
2009 Crestliner Superhawk 1900
2013 Polaris Sportsman 550 EXP
2008 Polaris Sportsman 700 X2