The slide hammer can work good, but drilling holes method should be last resort, i feel you will end up needing/spreading so many holes all over the place to get that straight-ish, you will just end up with a bigger mess to fix.
Another way you may be able to try,(but need access to a welder) is to tack weld a washer on to the panel, then insert slide hammer in to the hole in the "washer" and pull that way, perhaps if you buy a box of cheap washers, you can afford to leave them all on allowing you to pull in different locations to ease the damage out by spreading the pulls.
Getting back to your roof, while i think of it, im pretty sure "Ti" model Qs came with clip on chrome covers for the roof gutters, may be worth keeping in mind for later to cover damage.