Causes of toe cramps

Been doing longer rides of late, I am always prone to cramps and have to drink a lot (no not alcohol or plain water either) to fend them off, on a recent long distance ride I was on the verge of cramps in my toes the whole time (it felt like my toes were on fire at times, but plenty of fluids would fend it off, it was a hot ride mind and I downed 5.5litres in 11 hours and didn't pee once) and was wondering if, apart from other causes, it may be caused by cleat position (SPD, shimano shoes) loading my toes up to counteract pedal force. Any thoughts before I go ahead and move my cleats back a few mm (if there is any room on the sole!).