Meh, nothing structural so far. Give the worst looking spots some wacks with a hammer, poke around with screwdriver, pry bar, whatever. I'd be surprised if it didnt have years in it yet. Once youve poked around, mechanically removing as much rust as you can then paint, or your coating of choice. Or just give it a good spray with something oily, get into as much of the inside of frame and body panels, door bottoms as you can. Itll look a lot less scary and prolong the life exponentially. Rust Check brand products are a Canadian standby, they come in two flavours, a light runny red fluid and a heavier 'amber' that goes on almost like an oily gel. Red stuff for inside for inside of panels and such. Can be had in aerosols for convenience or larger quantities if desired. By the pail or even the drum. Also know as oil based rust proofing.
Can use whatever is cheap though, wd40 is too light. Old farmer method is used engine oil, I've seen people use chainsaw bar oil and Atf as well. Messy. But works,. Expect anything runny you spray into panels to drip for a day or two, not exactly street friendly.
Being in TX, once youve gotten ahead of the rusties it shouldnt be a problem for some time to come.
Ps, Fluid Film is also a Canadian product and has very similar sticking/flow characteristics to commercial rustproofing products such as 'amber' Rust Check. Much tider than the runny stuff.