The ingredient in GasX, simethicone, breaks of the gas and can reduce the build up of gas. If given early enough in the bloat process, the reduction of gas can be effective in preventing the torsion (flipping of the stomach). With the pills you can just give one to the dog. I like the liquid because I can draw it up in a syringe and shoot it into the back of the throat.
I use this first aid kit that I purchased. Pro Model 3000 - Outdoor Safety
I supplemented it with GasX pills, liquid simethicone, a bloat tube, extra bandaids (for me!!), EMT Gel, one of those portable phone charger thingies, a bottle of water, and small amounts of metronidazole, tramadol, amoxicillin, and tylan. I keep the entire kit in the dog van.
Is it overkill? Probably. But I'd rather be over prepared than not.