Ugh, it's gonna be harder to get away from proprietary maps than I thought. I removed all mapbox data from boydsmaps and am only using their API to display the 3d maps that I host myself. Turns out, everytime somebody loads one of these maps, it creates a billable event just because the Mapbox API is being used.
Just stumbled across this while looking for something else. This is my nightmare scenario... guy starts a website using Mapbox, site goes viral and he receives a $11,000 bill for his use of the API.
I mean, it's a long shot, sure, but not inconceivable. There could be some kind of front-page-story event and a major publication could link to one of my maps, easily exceeding the mapbox 50,000 monthly limit. At least Mapbox hasn't adopted the policy of requiring a credit card on file to automatically bill me (HERE and Google have that requirement).
In the short term, the changes I've made have reduced mapbox usage from about 10,000 loads to around 1,200. But I really need to transition completely away from them. Had quick look at the open source version of their old API and it looks like that might work for me. Will dig deeper into this in the coming months