Works fine for me
What you have in mind will work out just fine...Just remember that you will have to sand out the whole car..not down to metal..when you get around to painting..
SPI has a 7 day recoat window..after that it needs to be sanded..this is not an issue for most of us as we are going to sand it down anyway when we go to final..Just enough to "break the surface"
Just for the record what you are planning is what I am doing...
I have tried most all of it and now do what is known to work..