That's a good approach. PP or Dawn dish soap should remove most old wax. If you want to be ultra thorough, wipe it with a water & IPA mixed at 50/50 before the SiO2 spray.
Then use an SiO2 like TW, and maintain. That will be all you need.
My current regimen is like that above.
I am currently using this for the initial coat:
Buy Turtle Wax 53409 Hybrid Solutions Ceramic Spray Coating - 16 Fl Oz.: Waxes - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
smile.amazon.com
And this every wash as a drying agent. Uber cheap for $9 and at two squirts per panel, 26 oz go a long, long way:
Buy Turtle Wax 53409 Hybrid Solutions Ceramic Spray Coating - 16 Fl Oz.: Waxes - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
smile.amazon.com
Again, keep it simple and enjoy your truck
Cheers,