For a winter wash you may want to consider getting the Worx Hydroshot. The advantage of this type of pressure washer is it is capable of drawing water from a bucket. This will allow you to fill up a bucket with warm water (20-25 deg C) from your sink for your pre-wash step. The pressure and flow of the Hydroshot is fairly low but adequate when using 15 deg pattern to remove build up on the sides, front and rear of vehicle. Another tool to consider is a small pump pressure sprayer for applying ONR pre-soak solution. Any of the garden type you can buy in the hardware store will work (typically $5-$12) but the iK 1.5 Multi Sprayer is a far superior tool if you don't mind spending more money (typically $40-$45).
This is my winter wash procedure:
1. Prepare ONR solution at 256:1 ratio (standard) in bucket using warm water.
2. Fill second bucket with warm water.
3. Fill multi-sprayer with warm ONR solution from bucket. If you feel you need higher dilution ratio, add some more drops of ONR to sprayer. I used to use higher dilution ratio but typically stick with standard for pre-soak these days. Apply pre-soak to all panels with visible dirt build-up (typically front, lower sides and rear). I don't usually bother with pre-soak on windows and roof unless there is visible dirt.
4. Using Hydroshot hooked up to warm water bucket, rinse off pre-soak/dirt from vehicle.
5. Wash vehicle panel by panel starting from top using warm ONR solution and BRS
6. Apply Hyper Seal as drying aid and dry vehicle panel by panel.
7. After all paint clean, using cheap microfiber towels in remaining ONR to wipe down tires and wheels. Use Hyper-Seal on rims as drying aid.
I would consider moving the Hyper-Seal to a different sprayer. I find the supplied sprayer lays down too much product. Or consider just doing a partial pull (third to half pull) of the trigger per panel.