Great tips Tom.
I second all of that, and wagtail flipper.
I'm wfp, i put pure water in trigger spray bottle with gg3.
Have a small bucket with scrims, trigger bottle and W5 (lidl's version of fairy), scraper, shoe covers impress, bucket makes it easy to carry stuff about.
If regular repeat inside 1.5x ok.
otherwise go for two times or say will do inside for same outside price/ 1.5 times if they will let you do on heavy rain day when you can't work outside.
Would have to be on a phone call.