We just attended the Backbone Bluegrass Festival in Strawberry Point, Iowa. Festival is held on private land just outside Backbone State Park (Strawberry Point, IA). Runs Fri-Sun on the last full weekend of every July. Good entertainment, groups played multiple sets, but different songs each time. Quality picking for the bluegrass fans.
As for RV options:
1) Limited spots on the festival grounds. Very tight, only a few 30 amp spots, no water or sewer. No WiFi, 1 bar cell at best.
2) Backbone SP has a nice campground with water/electric spots and a dump station.
3) We stayed at Lil Bit-o-Country campground in Strawberry Point. About a dozen spots, but very well maintained. All full hookups, sights are level to nearly level. Our spot (20) had 1 flaw - sewer connection was basically uphill, but fine beyond that. $30 a night, would stay here again.
2021 Forest River Wildwood Heritage Glen 24RLHL: 810-825# TW, ~7500# GVW
2020 F-250 XLT Super Duty SRW: 7.3 V8 gasser, 3.55, 10spd