Long time 4Runner owner converting to a 04 Taco

So I've had 3 3rd gen 4runners now and have loved them! I've been in the market for a newer vehicle and came across a very nice 04 trd. Now I've read the buyers guide that's posted here but my concerns are that yes the frame fell under the recall but was never taken care of by the past owner due to the fact that he lives in the south where rust isn't a problem. Now the recall is basically voided due to the fact it wasn't coated. Now I'm from PA, and I'm curious to what all of your opinion's are as far as the life expectancy of the frame goes if I were to buy it this weekend and bring her up to the salty roads of PA. Minor surface rust is evident and I've been reading about an undercoating product name RustBullet. I have also read a lot of good reveiws on this product. I think I may just paint a few coats on and hope that the added protections at least cuts the spreading of severe rust. Any opinions are welcome and too any other tips tricks and things to look out for as far as buying a Taco is greatly appreciated!