Good Morning All,
Okay, just got off the phone with James at Whisper Wash, and he was very helpful. Cliffs Notes:
His solution: Tighten the hardware where the bracket and nylon spacers are (mine is pretty tight, but will tighten more). He says that will hold the cover in place, so to speak, and keep it from dragging up on aggregate on the concrete. Also said I shouldn’t need the additional weight at all.
4" for every 4 GPM: According to him this is myth. It is more about what you are cleaning. Of course weight and lift are factors, but he said he has seen guys get results from a “mondo” with a 4 gpm. If you haven’t heard of this bad boy, check it out here, a smooth 2k gets you into one of these: https://whisperwashonline.com/product/whisper-wash-mondo-force-49-surface-cleaner/
It all depends on the surface. To others point on here (IBS) he said a 16" cleans so well because it has the shortest swivel bar, therefore traveling the fastest (more rotations over an area as you travel). Makes sense if you think about it.
He has heard of guys abandoning a 28" big guy on a job for a 19" because of the resiliency of the soiling on the surface requiring more rotation to achieve a result.
Anyway, sorry the Cliffs Notes got long winded, but the guy was really nice, and more than happy to help and to discuss pressure washing in general. He also advocates pre/post treating surfaces.
Hope this helps the forum. And thanks everyone for your responses. Much appreciated!