The sensors are very small....one can be placed behind the plastic on each side where there are those hangar bay doors on the upper hull. If the plastic is thin enough and not much paint the IR may pass through. On my Enterprise refit I put those in the base behind the plastic and the IR was able to pass through and work. You can put one each side and in the back where the engines are. If that doesn't work you can still put behind plastic and drill a tiny hole through it to expose the IR sensor or maybe mount them in the trenches and disguise as a greebie. I will do one of those methods.......Test and see which one works when I get to it