OK, I'm going to be a bit contrary.
Second major possible problem will be bearings. After the first 30 miles and then every time you stop for gas, put your hand on the hub. It'll be warm, perhaps uncomfortably so (120 degrees perhaps), but if you leave any skin behind or end up with blisters, somethings terribly wrong and you need to fix it before you go anywhere else. It's likely either brakes or bearings, but you don't want to pull it any further until you find out which and resolve their issues. Buying one of the inexpensive infrared thermometers like this
will keep your hands clean (and unblistered) when you do this check.
ALWAYS, ALWAYS use rear tie-downs, and make them tight. If you don't believe me, simply drive behind an untied boat on a rough road - the boat will be bouncing 2" off the bunks and slamming back down. You want the boat and the trailer to be a single unit moving together, not two independent units bashing each other. The boat isn't going to bounce off the trailer going down the road unless you're in an accident, the straps are there to prevent that pounding - and to keep the boat and trailer together in case of the aforementioned accident.
Don't drive too fast - higher speeds cause drastically higher tire temperatures and likelihood of failure. Make sure the tires are inflated to max sidewall pressure (cold), drive the speed limit or below, and your day will be a lot less stressful.