Had basically the same experience, sat all winter and until July. Fired right up and no issues for a 7 day trip, just topped off the fresh H2O (I'm on a sweet well and always take it from home), added our chow and off we went. Went again in August and just got back from another week. 1854 miles in three trips, 180 gallons of diesel and my only issue is a non-functioning porch light....LOVE these vintage coaches! Routine maintenance/cleaning when you get back does pay off.
Safe travels and regards to all'
Chief G CMSGT Retired