I think this is a pretty tractable problem: plenty of non-Indians love Indian food for the spice, and anecdotally, I've had plenty of food like "thai hot" pad thai that's too hot for my Indian coworkers.

Palates will vary, but I'd expect the typical 1-4 pepper scale would give most people a good option. If carrying four variants of every item is too much of a challenge, the meals could include optional spice sub-packets.