Eugh, sounds a bit complicated
Better to work out the to-hit-hull and to-break-stealth scores, decide if you're firing against hull or stealth, and roll. Going back and comparing original hull score then seems like a step backwards.
It does make sense for precise to not work when going against steath, I agree. But in the example given, a precise weapon would be better than a SAP precise weapon. That is just wrong.

Better to work out the to-hit-hull and to-break-stealth scores, decide if you're firing against hull or stealth, and roll. Going back and comparing original hull score then seems like a step backwards.
It does make sense for precise to not work when going against steath, I agree. But in the example given, a precise weapon would be better than a SAP precise weapon. That is just wrong.