As an aside, check out Strelets A001 through A004 in Michigan Toy Soldiers - their 1/72 8" howitzers look just right for the scale, are relatively inexpensive, and can be assembled without the wheels easily. They have a nice break away assembly diagram on the back of the box and I'm sure our enterprising folks from IG could come up with a 18 mm version based on all that info. I'd bought A002 American 8" Howitizer for my Yeti battalion (Canadian), with the hats looking just right for Royal Mounties manning the gun. Boom goes the Martians lend into a trap!
One comment on the excellent pic of the Landship above - shouldn't there be some sort of retrieval crane or ramp to get the mono back on the ship at some point. Of coarse you could have an engineer crane or railroad crane setup to do that as a 'talk around'. Just saying.
I think the height of the mono's platforms is too high for them to jump off without serious damage to the vehicle or the driver (i.e. vetebral compression fracture/disc rupture or even aortic dissection from the impact). I was thinking a launch and recovery crane between the mono platforms is essential (add would look really good).
I'm of two minds on this. Frankly, I think both systems would look good - the crane between the vehicle locations and the ramps as boxholder mentions. That way the ramps would allow quick deployment and the crane could recover between battles. I assume that the ramps are pulled up after 'launch' to allow maneuvering.