I've battled cramps for years also, racing in TX summertimes makes it a problem we all have. I've read every article I can find, tried all sorts of concoctions. Here's my 2 cents.
(1) it seems that not many people are talking about pH. I think that's important in this context. We are talking about the nervous system here, which controls the firing of the muscle. The muscle is not the problem, it's the contractions. For me, once I started reading on food / diet acid / alkalines, and changing my diet based on that school of thought. For me, it has really helped reduce but not eliminate cramps.
(2) there is a physical component. IF there is the slightest thing "off" in your position, or overall fitness, or muscle imbalance, then when the body reaches the breaking point, one muscle will be the first to go. For me, it's always the left sartorious. I have an old knee injury on that side so it makes perfect sense to me, I use the sartorious (unconsciously) more than a cyclist really should, as it helps stabilize my knee.
Funny thing about that - ya know what else messes with my sartorious? Sitting in a desk chair all day.
(3) it's not just "the ride" that causes the cramp. It's your whole life. Desk chairs, long drives, diet, sleep, posture habits, core imbalances, bike position, crank length, cleat position, they can any or all contribute.
(4) experiment. you are a sample size of 1. read and try things. I settled on a homemade mix that works for me, and I do carry and have successfully used mustard packs.