We use the counter top ice maker. It makes ice faster than the ice maker in the gas/elect fridge. We use quite a bit of ice.
We make the ice in the counter top ice maker, empty the ice into 1 gallon zip lock bags and store it in the freezer.
NOTE: These ice makers don't exactly make unlimited ice. The process is: You add about a gallon or so of water to the ice maker. It then makes about a half a pound to a pound of ice in about 10-15 minutes. After about an hour to an hour and a half the ice bin fills up and ice making process stops. The ice maker does NOT keep the ice frozen. That is why we empty the ice into bags and put it in the freezer.
Due to the way the ice making process works, you can't make ice while driving. The motion of the driving keeps the water moving so the ice does not form on the freezing fingers. You might get a tiny bit of ice, but not enough to make it worth while.
We do a lot of boondocking, weeks at a time w/o elect hookups. When we have good sun to charge our batteries we make ice for 2-4 hours and fill up about 3 one gallon zip lock bags and put them in the freezer. Keep us in ice for a few days.