The LHD vehicle in a RHD country is not a deal-breaker, IMO, and certainly not worth taking the hit on selling a year-old vehicle. It will be weird at first, but you should get used to it pretty quickly. If either you or your wife are easily-rattled or not very confident as drivers, it might be an issue, I guess. Roundabouts seem to fluster a lot of American drivers, too, so be aware of that.
The bigger problem I see is the size of the truck. It's not huge, by American standards, but will feel much bigger over there, trust me. There will be some places you simply cannot drive, mostly older city centers and that sort of thing, and parking will be tougher than with a smaller car. Living on a military base, you'll be fine, and out in the country, you'll be fine. Just understand that there might be some towns you come across where it makes more sense to park as soon as you can and do your sightseeing on foot.
But still, I wouldn't sell a one-year old truck just because I was going overseas for 2-3 years. I would make it work.