I just took it upon myself to post a link. Can't say as I know what if anything the product will do to the friction factor of your tramp. I have a mesh tramp, so for me it's a moot point. It is my intuition that a respected place like Murrays would not post something that would create an undesireable side effect.
I would NOT suggest anything like ArmorAll. Products like that leave a residue that won't harm your dash board but I cant imagine is desireable on a wet tramp.