I had the same thing when I made a cupboard to fit the Genny, I didn't want it stand out against the fake wood on the interior I bit the bullet temporarily by just varnishing the ply, hoping I didn't get that dodgy home made varnished ply look, by shear ars the tint I chose while not a match actually blends in, is hardly noticed at all , so it doesn't look too daggy.............So maybe look for something that blends in and doesn't make a stark contrast, trying to match can make things stand out, either that or the old fall back, a towel rail.....