Leave the electric controller on, you might want it if you ever want to haul an equipment trailer or something else with electric brakes. The 6 or 7 pin connector you probably now have on the van should stay--just get an adapter plug to go to the (probably) flat 4 wire plug you have on your boat trailer with the surge brakes. I suspect you will find you are ok with the surge brakes for towing your boat, it will be better than your old van, I'll bet this one scales 2,000# more than your old Chevy. It has brakes to match it's weight and will be a good deal better than what you are used to. I think the 4.10 ratio is a good idea for what you are towing, my son has a 2001 F-250 with a chipped 7.3 Powerstroke with a Utility body which has the 3.73 rear, uses it to haul equipment on a flatbed trailer, and it does pull the load, but I think it would be better with a 4.10. It will be interesting to see what kind of fuel mileage you get with your new rig.