If you are doing routine maintenance and upkeep on your trailer, there is not too much more you can do to prepare for a trip. I would also make sure I was maintaining my truck just as well.

I think having an emergency road service program like US Rider is always a good thing as well. I have had it for six years, but have never had to use it.

Being that you have a 2002 trailer, would pretty much tell me that you have rubber torsion axles.  There is little to nothing to go wrong with these axles, unlike the old spring/shackle type axles.  Those axles, after a lot of miles had wear issues with spring hangers and bushings.  Even leafs in the springs would break if hauling overloaded a lot. 

Inspection of your light plug and wiring is a good idea also.  A poor ground on lights, or corrosion in the plug can be a small problem, and result in "winky/blinky" lights.

Doesn't hurt to get down, and look unerneath your trailer also.  I hve a friend that did this very thing, and found a floor plank that had broke, but hadn't gave way, due to floor mats being on it, but had he not noticed it, the next trip could have been a disaster.

Do a good walk around and look for cracks/broken welds.  Cracks will result in larger cracks or breaks if not taken care of.

Know what pressure your tires are rated for; and also what speed rating they have.  A lot of trailer tires are rated for 65 MPH.  If your used to driving 70-75 on the interstate on a hot day...........your asking to have a blowout.  We repair/replace a lot of trailer fenders in our shop, due to blowouts, and a lot of them could have prevented with the right tire pressure and staying with the speed rating of the tire(s).

Good luck on your trip "blackcows" (my favorite color of cows).