Dear Wsmith,
1. Copy Business Type from Prop to an eVar using Processing Rules and set the expiration of the eVar to 'Never'. Make sure that you capture the Customer ID (After Authentication) to tie the visitor profile (Visitor IDs) so that even if Customers delete the cookies/cache, the server persistence will continue. I would recommend.
2. Or Create Visitor Container segment with Prop. Again, the delete the cookies/cache by the users will have the impact until you Customer ID (After Authentication) to tie the visitor profile (Visitor IDs).
3. Or Ask your dev team to pass the Business Type as Data Layer, on every page.
Thank You, Arun.