I built one for a Helix 5 that I use on my Lund, my kayak and canoe, and I use it for the GPS on the ice. Had to buy 3 different power cords, an extra transducer, and an ice transducer to do all the above. I used a wide, trex decking fascia board (waterproof) and cut it into a circle that fits into the bottom of a five gallon bucket. Then I used a woodworking router to make recesses for a battery and the ice transducer to sit down into and 1/2” webbing with buckle to secure the battery.
I mounted a RAM 1” ball mount on it with the long riser to hold the Helix unit. The bucket with an aftermarket lid protects it better than a soft shuttle but I pull it out and mount it to my four wheeler rack with a U bolt whenever I need GPS, and the ice ducer reaches about 7’ away from the four wheeler if I’m running around, drilling holes to check depths.