Does FCA offer a rear door spare mount? I would check with them, and price compare the two products. A mount and an extra (full sized) tire will use up some of your GVWR weight, and your OCCC will be reduced by the same amount. That's the only con I can think of.
2018 (2017 Sprinter Cab Chassis) Navion24V + 2016 Wrangler JKU (sold @ ????) - 2016 Sunstar 26HE (sold @ 4600 miles) - 2002 Roadtrek C190P (sold @ 315,000kms)