Les, that's a pretty impressive solution to the trailer battery charging problem. 4 gauge wire is a hefty conduit! How much did all these mods cost you, if you don't mind me asking?
Edit: I just looked up the DC-DC charger, and see it can basically replace a solar controller, so that's another great way to give it power (and charge your battery) while camped!
Hi-Lo 1707T - Tire Minder TPMS on Tow Vehicle and Trailer, 300W Solar Battery Charger, Equal-i-zer WDH
2014 F150 Platinum 4x4 3.5L EcoBoost SCrew