Adding fields to a table

I would go with adding a new table. I have no real basis for this, but i have seen several other add-ins that do this successfully.

HI, a client want to implement a VIP program using RMS, unfortunately the number of fields that the customer table have are not enough. One of the solutions that the It guy of my client is considering is to add field to the customer table. I have my serious reserve about this but want to give him an apropiate solution not a "no, you can not do that". Do you guys had an experience with this kind of problems? how do you solved it? Thks in advance for your time