my 2 cts,buy the converter that is key activated and I believe it comes in a 30amp version,you might be alittle light at 20 amps for all the stuff you want to run.The main feed in to the converter both pos and neg are 10 or 12 ga depending on the converter,the feed to the ignition switch is 16 or 18 ga problem,plus the increase in amps across the switch.As far as the radio memory the only way is with the aux battery that Andy mentioned or to run the converter full time.If you relay the converter to an extra switch you can have it all when using the cart and switch it off when stored,a full time converter will kill a pack in a short time of no use..Dave