I like to use oil based drying aids specifically for this reason. The solvents will help clean oil based residue from the paint. Using the optiseal will help. I've started to use and prefer 10min. Sealant
A surface that sheets the water off before the water evaporates will leave very little mineral residue behind. Contrast this with beading that will concentrate the mineral residue in a small area and maximize the chances for etching.
I've yet to see any single advantage of a product to bead water.
Spray directly on the panel. 2 sprays typically per panel.
I'm currently using McKee’s 10 min sealant and liking it very much, but does have bit of a chemical smell. Optiseal is water clear with no smell.
Towel kleen is only a pH of about 8 as I recall when I tested it. Would recommend a presoak of water based degreaser with Oxiclean for a few hours, and wash with same.
This is how I'm now washing with great results. Need strong cleaners to attack dried sealants etc.
I like to use a foam Cannon but I've yet to find a pH neutral soap that does much. My favorite is a residue free laundry detergent that is about pH 10. This even attacks break dust and doesn't damage lsp.
Optimum Power Clean is another good product for a foam Cannon.