On a steep ramp as you mention using, the “sweet spot” where the boat won’t float off on it’s own, but can be nudged off with the motor as you climb in is smaller. The steeper the launch, the more the nose of the boat digs down into the trailer (and dry carpet)as the rear begins to float. You will ultimately just have to back in a bit further. I would never mess with spraying something on my bunks.
My process with bunk trailer:
1. plug in, straps off, boat loaded with gear, safety chain off (in staging area of lot nowhere near the ramp)
2. back to the point where the back end just begins to float (close to dock). Parking brake, then truck to park.
3. step into boat from dock and unclip strap.
4. walk to the back of the boat and my weight will often be enough to float it off (on my regular ramp). If not my regular ramp I will start the motor, nudge it off, and tie off out of the way.
5. park truck
***Steps 2, 3, 4, take a combined ~60 seconds at the very most where my rig is on the actual ramp.
***If someone is with me I have them stand and watch, or maybe park the truck after if I have something I want to organize in the boat quick. Anything else and they will make it slower.
***If you have a bunk trailer and someone tries to sell you on a Drotto, don’t listen to them on that, or anything boating related.