Well, there's always the Ardennes ...
Any forest adjacent to civilised/populated areas will have roads, fire trails, dirt roads etc. They may not go exactly where you want, but will probably get you there eventually. The thinner the vehicle the more such trails it can take, and the easier time it'll have. Strykers tend to be thinner than Abrams, no?
And anyone who didn't dump google map images of the ops area before movement isn't cheating ;)
But neither can go casually bumbling cross-country through old-growth forest, true.