Hi.
OK, I have done something similar for Marks & Spencer in Marbella store. I think the only way to do this (apart the Generic Customer with Price Level B) is creating a hook add-on that can bi activated (On/Off) via button on the RMS POS and when activated, just before opening a Tender window (or similar) the add-on should run trhough the Items selected in the Transaction and apply the Price Level 2 (if any assigned) for each of the Items. It could be done also to be applied after every new Item added to the Transaction, but I think You will have to have a button for On/Off the ad-on...
This is just ideas, of course you will need to sit with your RMS Partner and discuss is in details, but still it have to be through an hook add-on.
Kind regards, A.