[Mixed Bathing] I want to go to Secret hot spring "Hiba Senninburo"! Are there any recommended hot spring inns around Sukayu Onsen?

I would like to go to the "Hiba Senninburo" bath at Sukayu Onsen with a friend, but I'm not used to bathing in bathing clothes. I'm thinking of just stopping by the "Hiba Senninburo" bath to get a feel for the atmosphere of Mixed-Gender Hot Springs hot spring, then staying at another hotel and relaxing in the hot spring. Since we'll be traveling by car, it's fine if it's somewhere far away, like deep in the mountains. Are there any hotels with famous hot springs that are good to visit after visiting Sukayu Onsen? Since I'm focusing on the hot springs, I don't mind if the inn and facilities are a little old. I'd like a place that includes meals.