Robust, but still commonly available (at least in the US substitute with local flavor of choice if not US), would be switching it to SOOW cable. Some 18-16awg 4 conductor shouldn't be absurdly large, but still quite robust with the rubber jacket. Fine stranding, EPDM rubber insulators, chlorinated polyethylene(CPE) jacket, Oil, water, outdoor rated. Going beyond that, I would definitely start looking at continuous flex rated polyurethane jacketed cables, and even more resistant than that would start including stuff with actual armor.
Crane pendant cable may also be available in small enough quantities, and is pretty rugged. Available with either internal reinforcement, or external steel cables to support the weight of the pendant, or in this case, you could terminate the steel cables to the connector body, or pedal.