East of Twin there's a decent overnighter called Village of Trees RV Park, in Declo. Grassy spots, a few with a bit of shade. Gas station next door (convenient) and it has a little restaurant attached, takeout for campers. (Not sure, with COVID, if the restaurant is open, but I believe the CG is.) We've been a couple times.
West of Twin - someone mentioned Three Island Crossing SP, which is nice. Electric & water sites only; not sure if there's a dump station. It could be full w/o an advance reservation. Not sure if the visitor center is open - pretty interesting spot if so.
Also we liked Hagerman RV Park in Hagerman - big shade trees (but probably not enough to block satellite signals). Decent overnighter.
Rock Springs KOA is ok (have been a couple times) but we like Lyman KOA, a bit west of there. A mile or so off the interstate so less road noise, rural atmosphere, can fit almost any size rig. Not too many FHUs but friendly owners & quiet place.
