Honestly, having an accident on your vin record is not detrimental unless it was declared a total loss and sold with a salvage title. If there is an accident on file and no documentation showing severity or repairs done, that would draw down the value.
For example, I had a 2001 Tacoma that was hit in the side of the engine compartment. Whole front end had to be replaced. Did not affect the value when I sold it 5 years later. I was just upfront with what had happened and gave over all the documentation from the auto body shop.
On the other hand I had an 07 charger that my wife scraped the driver's side down our retaining wall. Mostly just paint and some dents. Took it and had the auto body shop repair and repaint, no accident was recorded to our vin. When we went to sell it, the first person that came to look at it took one look down the side and could tell that there had been repainting done. I couldn't even tell myself until he pointed out very subtle differences. We didn't have the documentation for that one, had lost it in a move. He walked away because he was afraid it had been in an accident that we were concealing.
Long story short if you are worried about resale value, I would have the repairs done properly and keep the documentation. Especially with anything that has to do with airbag deployments. If you plan on keeping this, then doing it yourself in stages is fine as well.