Out of radar range just fly up under a legitimate scheduled flight, remaining a hundred feet or so directly below it. Monitor that aircraft’s comm with ATC to anticipate changes in assigned altitude & heading so that you are prepared to mimic turns and climbs/descents.
Do it at night and the paint job will not matter. Do it during daylight and it will not matter until you are too close for anyone (outside of a military target with close-in air defense) to do anything about you.
Time to install some rear view and under carriage cameras.
I would say truckers mirrors but being a concrete mixer driver those too have blind spots, plus they are not very aerodynamic.
By all means FAA, install cameras!
get a radar in the ASS of your planes, not yours!