You could go with something completely no terrestrial. I once did a hover tank that, in addition to the expected light and medium greens, used a rust red/orange and a violet/purple as disruptives.
I sprayed the greens in the usual broad amoeba swaths but used my hole punch to make several masks in plastic stock with inter linked series of large and small holes and then sprayed the red and violet using those masks. In proportion the two colours were added much like the black and tan in the old MERDC scheme, thought the use of the masks made the effect much different.
The two colours were not garishly different in tone than the greens, so it really worked well as a scheme. Different, but it didn't scream at you. Very effective as a Hammer's Slammers off-world vehicle.
Paul