As you mentioned, I wrap the speakers with plastic wrap. I also do the tower and the wakeboard racks (3-wraps of plastic around the rack and break off going toward the back so the air doesn't catch the seam).

I also carry an extra rachet strap in case there is a bearing issue. Dual axle trailer, can remove the wheel, rachet up the axle and get to a safe place to diagnose.

I don't trailer with a cover. Last boat I did and it blew the seam apart at the threads. We leave the wakeboards and seats in the boat.

Carry a hammer, some basic wrenches if you are handy enough to fix things. Check tires and bearing for heat at each gas/rest stop.

I will do the rachet for the swim platform since I read that here.