Not sure how close you need to be to Twin Falls itself; if you can be about 30 miles east of there, the Village of Trees RV park (address is Declo, ID) is nice. Space for long rigs, a spot to walk to along the Snake River, convenient to the interstate, older but clean facilities for the most part. Not quite as tightly packed as some other private FHU CGs. Cafรฉ & gas station on the premises too.
2020 Toyota Tundra CrewMax 5.7L V8 w/ tow pkg, Equal-i-zer
2020 Lance 2375