As far as the terrain is concerned, the best way to add immersion ot it, IMHO, is YAP. Ok, it's not exactly high-res terrain as you meant it, but it adds lots of targets, AAA under nearly every bush, lotfs of new ground objects, ...
Talking about Flight Of The Intruder, after watching it for the 103rd time (approx.) last week, I started working on a little something for the stock WoV A-6A:
The goal is to try to recreate the VA-196 aicraft park, including those of the movie's heroes. So far, I've got Cool Hand and Morg aboard Devil 505, "Dooke" Camparelli aboard Devil 520, me (could'n resist ^^) and "Tiger" Cole aboard Devil 502. I'll check for Razor's plane. I've done Boxman, Coold Hand and Cole helmets so far.
Hey if you guys are fond of this movie as much as I am, maybe I could do your personal planes, with your name and moddex?