IOTA really only goes 14.6 then you have 15 minutes before it drops to 14.2 volts. The 14.8 is only the max if you hit it during that 15 minutes. Still an excellent converter.
With #6 wire (how long?) I would stick with 55 amps. I am not big on parallel conductors and neither is RVIA and NEC. Low battery will still take a solid three hours to get to 90%. Larger wire is better. Since you are pulling wire I recommend going #4 even #2 if it will fit the connectors. Also the 15 amp outlet limits you to the 55a version.
