I used to own a. 79 Bethany and loved it. If I remember correctly, the zippers are only undone if you were to replace a section, not each time you set up. There are Velcro tabs over the zippers and around the underside of the beds. The canvas may have shrunk, which has been mentioned. I think I could help you with the order of setup if you need that.
2010 Triple-E Regency GT29DBS
2009 Heartland Bighorn 3385 RL
(On Permanent Site in N. Georgia)