@Andrew
I'd not thought of Germy's work. Some possibilities...
I'd like to suggest this might be another occasion for thinking in other scales. A 15mm or 25-28-whateverMM fantasy multi-leg beast or sci-fi walker droid or device-on-tripod might well translate to a Martian tripod. I know RAFM has some remote gun droids that might be appropriate, and one could take a GW Tau disc thingy and add legs, but neither seem quite right. Vague mental images of radially spread six legged Star Wars and D&D beasts aren't resolving in to particular examples.
Feeling a bit groggy for reasons I can't fathom, so not coming up with lots of great ideas, but maybe someone else will feel pointed in the right direction.
Doug