To further reduce chances of swirls with the rinseless wash, spray down the panel with waterless wash.... The waterless wash will encapsulate the dirt, and allow for your wash mit to more easily remove the dirt. OR you can squeeze out your wash mit on top of the panel you are about to work on, then wipe it clean. another trick, if you want to use one bucket, fill up one bucket with a set of plush towels and soak it in your rinseless wash solution... use the towel folding technique to ensure you are not dragging the same dirt across the car, then keep folding sides. once you are done set aside the towel, and move use another one. tips: quality towels make a difference, nothing in autozone is good, don't bother with them. ragcompany or chemical guys makes good stuff. find a deal and buy those.
I can not stress enough, you must power wash under your car even if you do rinseless wash.
I bought something like this,
http://www.theunderwasher.com/ you can make it yourself. or you shove one of those things you wash your garden with under the car. (make sure your engine is cold).
I use to be a perfectionist with my paint, and always had it glowing, but after I saw what salt does to under sides of my parents 02 and 04 4runner, I'd take a few swirls if that means clean under belly.
another thing it is very very important that you dry the car correctly. I'd say 90% of swirls are caused by not drying it properly. microfiber does not mean you can drag it on the paint as much as you want because it is safe. Hand wash can be just as damaging as a machine wash. Look up the technique to dry your car. Take a wet microfiber towel (Yes wet), ring it out, spray waterless wash or your favorite quick details spray, grab as much as you can with the wet towel. you will notice wet microfiber towel obsorbs more... then put one spray and dry it with your second towel. AMMO has a great video on this. if you are cold, do not rush the drying step, take the water spots and skip the drying steps, (unless your area really has hard water), water spots are easier to take out than swirls.
lastly if you have to go to a machine wash, skip any thing that touches your paint, don't use their wax, and especially dont have them dry your car with their towels!!!!!!!!!!!!!!!!!!!! it is the drying process that induces all the swirls marks, most of them I would say.