Setting plan variables where?

I am just curious where to set data for a subscription plan? Stripe has meta fields so for each plan / subscription you could say planA allows meta photos => 5, planB photos => 10 which is dandy but I am using BrainTree so I am wondering where is the best / correct spot to set the the variables that make each plan different?

I have my plans table, which is synced with the BrainTree plans so if I manually add fields to my plans table like photo_max, listings_max and sync up with BrainTree all my custom fields are lost.

Just wondering how you guys out there do it. I suppose I could set up plan_options table and set the variable there but does not seem clean to me.