As one who has backpacked for years, way back when, we would pack it in and pack it out. I have always done the same cycling, use a gel pack or whatever, and put it in my pack pocket until I can find a trash can or get home to dispose of it.
Now,as far as the cost of the gel pack as opposed to, say, honey, that is another discussion unrelated to trash. Sure, why not save some money. But who knows, maybe someone might dispose of their 'honey' dispenser on the road as well. Just sayin'.