Thanks guys
So far I basecoated the pallet - I started with a bright green, which finished then proceeded to a duller green, then a bricky sort of red which is very similar to the primer used on steel plates and sections in shipyards, and finally a couple of patches of blue.
The result surprisingly worked, better (I think) than a monochrome solution - I can see this structure as one which is being built or modified or repaired. Detail paint is next.
I also found a solution for some of the flooring - these are plastic aquarium filter bed thingies, which someone had suggested in a thread I cannot retrace as suitable for flooring - they are! The first few I painted have a flaw - the undercoat spray did not adhere well; I solved this for the ones I still need to do by sanding the surface lightly before painting. I chose yellow as I seem to enjoy painting this, and as it brightens up the dark interior of the ship.
The unpainted 'beam' seen in this pic is something I still have to see how to best use - I have different plans for it.
As the square corner areas are a bit too enclosed to be useful, I will probably use the upper surface for more space on the 'board'. As mentioned above I will go for removable bits which will fall in two classes - regular and grimdark. Here is one of the latter which I am still considering - I might also use the trailer on which the model can be mounted and lay rails for it across the width of the pallet top.
This pic also shows more of the floor plates (still to be painted in this case - these were the undercoat test pieces) and a Futurama style travel tube.