I used Sikaflex on the top edges and side of the rear LED clearance lights that replaced the old bullseye lights. I did this about 4 or 5 years ago and that stuff is still pliable. I also used it, along with 3M tape, to cover the tilt mounts when I place solar panels on my Sovereign
4 years ago. It is still pliable. I have not had good experience with Parrbond because it looked like it was cracking two years after I put it on my aluminum rub rails.
I have a can of Acryl-R and plan to seal panels toward the end of summer so I can't say how well it would work