I usually fill the rivet holes with Trempro and install the rub rail. After the installation of the rub rail I put a little acryl-r or parbond one the exterior of the pop rivet. Then I put blue painters tape the top of the rub rail and side of trailer to make the top caulk joint. I use acryl-r or parbond for the upper joint. If you want a good looking smooth caulk joint when using the acryl-r or parbond, put on a nitril glove, lay down about 5 feet of caulk, quickly dip your index finger in mineral spirits, strike the joint and pull the tape immediately.
Steve, Christy, Anna and Phoebe (Border Collie)
1994 Classic 30'11" Excella - rear twin
2009 Dodge 2500, 6 Speed Auto, CTD, Quad Cab, Short Bed
Hensley Arrow hitch with adjustable stinger
WBCCI # 3072