Ben,
With the CST option on early Blazers, you get most of the stuff you mentioned as far as the power stuff. A/C was an option, though not particularly rare. What was unique about the Blazers is that they came with only ONE seat! If you wanted a passenger seat you paid extra......if you wanted a REAR seat, you paid extra. I don't know if they really sold many with just the one seat, but it is interesting that it was offered that way.
The tinted glass is a mystery to me. I don't know how big of a deal that was....
The rocker panel thing is weird.....It seems unlikely that the INNER rockers could be rotten and the OUTERs are fine.....any chance the outers were already replaced, to make the truck look better? Either way, it comes down to how "scary" it seems......nobody makes a reproduction of the inner rocker box, but a competent body shop should be able to fabricate something to copy it. It's a structural piece, so it IS important, but plenty of people have cut them out and replaced them successfully........it's certainly an area where you can "negotiate down" the price of the vehicle to your advantage.
It might be good to get some estimates from local shops for that type of work to make sure it's not going to bankrupt you....
Are there lots of other Blazers around to look at? Remember in 1969 there were only 4935 K5's produced, and it WAS the first year the K5 was ever made.....so that makes it somewhat rare. Perhaps the uniqueness makes it "worth it" to you?