There's antoher Hut near the Altmann. It's the Zwinglipass- Hut, 1999m south of the Altmann. It's a SAC-Hut of the Section Toggenburg. For more Information see http://www.kletterwand.com/sactoggenburg/zwinglipasshuette.htm
If you want to Camp, there's a beautiful site just behind the Seealpsee. It's within 1 h from Wasserauen. Just tell the people at the Hut at the upper end of the lake that you're there and for a modest fee you can camp where ever you want!