Colin,
I sure hope you're looking at it the right way because that's how I looked at it. My cab is on a dolly in my garage, out of the weather dressed only in etch primer. This stuff isn't very durable, but it's OK inside and dry.
You don't want to sand through it before you spray it with your 2K primer. Maybe a light scuff with a 3M pad.
I think the absolute best way to do this, in hindsight, is to blast and prep, etch prime and then immediately cover with a good 2K primer.
Any subsequent bodywork can be done through the 2K...Bondo included. It's common practice to apply body filler over the 2K, So why not let the truck sit in the shop in more than etch...finish it with 2K...it's then bullet proof.
Stuart