What I'd do:

If you're using multisite, have the main domain as just an HTML page, asking people to hit a button depending on where they want to go. You can do the password there.

Then buy three more domains, and point them at the first one...

Jamcustomers.com
Jamwholesale.com
jamservice.com

The only time they'll see jamwestfoods.com is when they check out...

Or maybe you could get away with just buying the wholesale and the service domains...