Guam, eh? Hafa Adai!
Leather is a LOT cheaper than a bodykit. Shipping on that kit alone to Guam will, literally, cost more than a leather kit will. Then there's the price of the kit itself, which is always misleadingly low. Most of the cost of a kit is in the shipping (even within the US you're looking at north of $300, to Guam it would have to be in the $500-750 range at least), mounting it, and painting it. And being familiar with Guam, I know that mounting it and painting it there ain't cheap (you're looking well north of a grand, even here)
You're trying to decide between a $600 (guessing) leather kit, and a body kit that will end up costing you probably north of $2500 all said and done. BIG difference.
And then you have to consider the upkeep of the kit. Even in the US, even in a major city that has nice roads, I still have to my kit repaired or touched up twice a year, to the tune of about $500+ each time. Fiberglass doesn't take well to any sort of physical contact. Just a good size rock being flung up can crack your bumper -- a $300+ repair. Rocks, tires on the road, pulling up too far when I park and touching the parking stop or curb, a speedbump that's a little too big and touches (and I mean touches it doesn't take much to crack fiberglass) the sidesills -- all $300-500 repairs. The roads on Guam ain't that great even on Marine Drive and they can get a LOT worse than that and steep inclines are rather common. I remember quite a few speed bumps there that would just take off the kit I have on my car now if I were to drive it there.
And there's no need to worry about the leather and the heat or humidity. It'll look just fine. Heat actually draws wrinkles out of the leather, not put them in.