I do something similar but moved away from two bucket method now in winter. My Van has a ceramic coating on as a base (Gyeon can coat)
1. Bilt hamber snow foam whole va
2. Clean wheels while foam is dwelling
3. Pressure washer whole van.
4. Foam again with and wash with a single bucket with shampoo.
5. Power rinse off
6. Spray wet coat on van one or two spray per panel and wheels and power wash off.
7. Dry van with a towel job done
1. Bilt hamber snow foam whole va
2. Clean wheels while foam is dwelling
3. Pressure washer whole van.
4. Foam again with and wash with a single bucket with shampoo.
5. Power rinse off
6. Spray wet coat on van one or two spray per panel and wheels and power wash off.
7. Dry van with a towel job done