Gasket\seal material that won't stick to paint if it degrades over time?

Question

I'm making a modification to the external GPS\Radio antenna on the roof of my vehicle.

The short version is that I'm going to use the mounting for the existing antenna housing to add a bigger roof top unit with a camera in it.

The existing mount is basically just a bolt that pulls the unit down against the roof tightly enough that it won't let water in. which is nice and neat since the unit is rubberized and deforms slightly to form a seal against the curve of the roof.

The replacement unit is solid and won't form a tight seal when bolted down.

I'm looking for a material that I can use to make a seal\gasket to go between it and the roof to keep the water out. But I want something that won't stick to the paint over time if it ages\degrades.

I've had previous issues with things pressed against paint doing this and either leaving marks and discoloration, or straight up taking the paint off when removed.

My aim is to end up with something that can be removed easily simply by undoing the mounting bolt, so that the original can be put back on with no fuss, and which requires no cutting, drilling, welding, or deviation from factory spec.

The manufacturer supplies 3M tape, which I'm going to keep keep in reserve as my plan B. So there is no need to discuss it here, I've used it before an am familiar with its properties.

Answer 1

Be aware that the main discoloration force for the car paint is the sunlight.

If you cover some area for a year or two, chances are it will be visibly fresher afterwards, with a distinct boundary, just because the paint under the cover degraded less.

White and, to some extent, black paints are safe-ish, everything else is pretty much not.

With this consideration in mind, the paint-safe gasket material I use for antennas and the likes is the silicone baking mat. Easy to cut into shape, soft enough to seal reasonably mating surfaces, resistant to heat (and to a great extent, sunlight) and, the material being food-safe for its intended use, one can reasonably hope it will not degrade releasing paint-etching chemicals.

It is also very chemically distinct from the car paint so sticking is unlikely.

Answer 2

If the 3M tape is waterproof, I'd use it. On several of my trucks I've put window visor rain guards on the doors. To attach these to the truck, they come with 3M tape to keep them in place. I'm pretty sure it is waterproof, because I've never had a leak past the window shades and the door (that I'm aware of). One winter, the shades got brittle and broke, so I was forced to replace them. While it took a bit to get the tape off of the paint, there was absolutely no discoloration, deformation, or issues with the paint due to the tape. This was a black truck, so it would have been very easy to see. Mind you, to remove it took a lot of elbow grease, as well as a product like Goo Gone to successfully remove the old tape in preparation for the new tape. There's also such things as decal removal eraser wheel you put on a drill to mechanically remove the tape without damaging the paint.