How should I deal with this rust on the underside of my older F-150

[Bluestream]

I have a similar issue with my F150. Due to surgery and some other health issues I haven't kept up "rust proofing" it the past two years. When I finally got underneath a few weeks ago to install the nerf bars I was met with a rusty scene. I'm thinking of going to Zeibart and having them do the job. I'm not in great condition to do it myself at this point. Nine year old truck, no issues other than this. Worth the cost?
Oh, and the Rustoleum rust converter is what I've used in the past to spray and brush on.

Forget Zeibart, that tar based product will only lock moisture in. I found that out the hard way.
Oiling is the only way this to stop the rust spread, if you want to go cheap, chain saw bar oil, has a tackfier for retention. If you want to spend, use fluid film or Wollwax