Do I need to sand this whole thing down!

Yes your in the right direction ,You have the epoxy going anyway so I would just do
most of it.
You may need to use the 2k several times to be happy with the bodywork.
After blocking (wetsanding) use water and wet area in a long swipe with a good rag and have a light at the other end and you will see what it would look like ,this will show any flaws.Some people use wax and grease remover for this.
The one thing also is even if your hands are clean they leave an oil residue so ware
some of those blue gloves. What will happen in the future is the paint will bubble and
lift in the hot sun in the contaminated areas.


Darryl