I agree with the others. Far too expensive to get a decent job .Not worth it on a 20 year old car IMO
A bodged job can look worse than an honest dent. I'd just treat the rust.
You could keep an eye out for a replacement tailgate, but it would have to be cheap ,including any cost of fitting , to make financial sense for resale value etc. .
On the plus side some drivers may keep their distance from a car with battle scars