I have the same issues even though I'm in Scotland , I like to wash the car on dull days when sunlight isn't an issue..... The remedy learned over time is.......preparation .....
1.Set up car at optimum point in drive.
2.Set up all equipment
3. Pressure washer connected to tap water hose via a common manifold, hozelock 6 way nozzle type.Snow Foam and lance on pressure washer .
4.Set up separate dedicated hose to output hose from Raceglaze Resin filter canister which is connected permanently to the Hozelock manifold, open hose end for maximum flow.This is mounted near to my garden gate so close to car washing area.
5.Prepare 3 wash buckets, Wheels , bodywork wash with soap, bodywork cold rinse.
6.Snow Foam car all over and in arches , underbody , in fact any crevice at all.
7. Have a coffee while admiring how the foam leans most of the much off with a mucky mitt on the car .
8.Pressure washer rinse at mid pressure ....
9, Wash using two bucket method on top half of car . Glass, Roof, Bonnet, upper tail, bodywork
10, Secret weapon part.... switch water over to Water Filter hose circuit and rinse all the soap of top part of car as you go down the car ... this totally reduces water & soapmarks but you have to be quick .......
11. Continue washing using soap / Rinse method and observe no water marks on your P&J.
12. Continue to wash lower half using 2 bucket method
13. Clean & rinse wheels
The beauty is ,with the water filter , No toweling or Chamois is required ... the paintwork shows no water marks as the water just runs off it...
I find that although it makes washing a hurried affair if its sunny , its worth the effort as its clean and no drying soap marks on the gleaming paintwork ...
try a water Filter and see what I mean .... I wish that I had one many years ago ... !!