Thanks guys, I appreciate the comments and suggestions.
Tom/Nick, I've looked into rock moulds from Woodland Scenics and Bragdon, but they seem to be difficult to get outside of the US, so I bought a few Woodlands ones. I think I should be able to get a decent variety of using combinations of the various moulds.
Nick, I think the second photo would be a great scene to model, however I think I'll have to compromise for practicality's sake. For safety reasons, I guess vehicles stay a set distance apart so a bomb or rocket cannot damage all of them. This however lends itself to pretty massive dioramas, and I don't have the space, time of money to build something so large. With that in mind here is my compressed layout idea:
The display area measures 460 x 260mm and will set on a raised platform of styrofoam. The height will vary from 150mm to 100mm (left to right). In front of the curved road will be section of cliff face. The pick-up and majority of the figures will take their place behind the convoy. I want to build something that is interesting and can be viewed from any direction, rather than just from the front.
Paul, don't worry I plan on loading these 3 up fully! The one with the hatch open has been filled with packs, jerry cans and water, and I have a cooler to go in as well. I'm also going to have a few packs and cots tied down on top of the boot lids.
^ Sorry, but I really like the Meng decals - they're minor things but add a lot to a scene!
Cheers
Anirudh