Underside wash/rust preventative?

I got a new (to me) 2005 Tundra, 180k miles, on Saturday. From what I can tell, it's been kept in a garage the whole time, and is allegedly always a Texas truck. It's very clean overall, and is an upgrade (although I'm having to get used to the smaller windshield and eye-level rear view mirror creating a blind spot).

The frame is pretty well rust free and looks very clean and solid, but a lot of the bolts and other parts on the underside look like they have exterior rust. There's minor surface rust on the drive shaft but it looks OK for a 19 year old part to me. The exhaust system is the worst part, but I think that's typical.

The frame is pretty clean, so I'm assuming it benefited from the recall I've seen mentioned online.
I am also not sure this is rust, because - see picture one below - even the rubber on the spare tire is reddish! Maybe some parts are attracting dust/gunk more than others?

What's the best way to get this cleaned up and protected?

 

If it were me I would spray the undercarriage down really good with a power washer to remove any lose dirt and get a couple of can of rust converter and call it a day.

 

I had an 04 tundra that I traded in three years ago here in Missouri, which I’m sure we get more snow and ice than Texas. and my undercarriage looked much better than yours. Are u near the coast?

 

Spending a lot of time at the beach can cause some of that. The response above from Maverick345 is a good one.

 

Supposedly the truck belong to an older gentleman up until 2020, and he lived not far from here (E. TX, humid). So far everything else the seller said has been accurate. It's always possible that the older gentleman had a second house on the beach or up north where they put salt on the roads. No way to know!

Are all rust converter sprays about the same?

 

I use Fluid Film or PB Blaster Surface Shield. Been thru 5 northeast Ohio winters and still looks good. Been using since new when purchased. Laserwash weekly.