I've never played A&A Minis, but I do play Squad Leader. The terrain/LOS rules are similar, so perhaps you could do a similar thing with A&A Minis maps. In addition to allowing terrain to flow into adjacent hexes (which is most common), ASL sometimes gets around terrain rules by using historical special rules. Historically accurate maps sometimes will create an unusual terrain type or an unusual combination of terrain types. This is because historically there existed more than one terrain type in a hex. If you are trying to recreate a historically accurate map, then you could take this option - make special rules describing how to play with the unusual terrain type or unusual combination of terrain types. However if you are not trying to recreate historically accurate terrain, I would not recommend this approach.
Also, if you are looking for different terrain types - the VASL Map Cabal site has the Squad Leader versions of the terrain types. The terrain art there might be worth looking at when making patterns for woods/grain/marsh/whatever.