Yes I did modify and Ice chest. I got one that is small enough that you can still get around in the cabin.
I take one gallon zip lock bags and fill them with water and freeze them. They last a lot longer than bags of ice.
I did hard wire the unit in.
I got my unit directly from Innova Tech, and I can't remember what I paid for it, but I think it was something close to that.
If you still have my telephone number give me a call, and I can give you some pointers about the two different ways I installed it. If you don't have the number let me know and I will send you an e-mail with it.
jeff@steelware.com