Here in Calif I see 4runners in yards pretty often with rear seats still there. Often times the condition isn’t too bad, especially compared to the front.
The only advice I might give is watch out for aftermarket seats. I think the quality is rather meh. Back in the 80’s we saw a lot of 2nd gen Supras and 1st gen 4Runners get stolen and stripped of interiors. Seats, radios, etc. Toyota didn't offer assembled seats, so insurance companies would often source out suppliers who did. The big giveaway that the interior may have been stolen at one time is if the seat brackets have parts stickers on them or if you see regular hardware store-type bolts holding the seats together.
