red to + and white to - should be correct. Are you sure the battery is overheating? Its normal for a fully charged battery to produce some hydrogen gas. The converters are set up to do that so that the battery electrolyte gets mixed. That's why you have to add distilled water occasionally.
If the battery really is overheating, what I'd suggest is to disconnect the battery, plug into the 110Vac circuit, and check the voltage and polarity on the disconnected wires at the battery end. Don't let either loose wire touch the frame of the trailer. The converter should be trying to charge the battery so you should see 13V-14Vdc there. In case there is something wrong with the converter itself and it is putting out too much voltage and causing the battery to overheat I'd suggest pulling all the other fuses in the distribution panel first as well.