Just finished doing mine using Hengs Rubber Roof coating.
Thoroughly washed the roof using the usual car wash soap.
Rolled on a 25% clorox/water mixture to kill all mold or anything organic. Mine had LBTs (little black spots).
After drying gave roof a good rinse.
Next came the Hengs. Did not remove anything. Nothing was leaking.
Applied the Hengs over everything using a short nap roller like I use for applying boat bottom paint. The Hengs is thick stuff. Smells like silicone.
Three coats applied. Might get another gallon & make it four coats.
Did the slide tops as well.