First: Going to 24 volts for the RV systems is a MAJOR undertakign, Several devices are hard to find in the 24 volt models. (Water pump, Furnace, Fridge and water heater control systems, A/C controls)
but that said.
When you wire thigns in series, be they batteries or Converters, to get a higher voltage there is an operating word IDENTICAL you must remember
You do not put a group 24 battery in series with a Group 31 to make 24 volts
Nor do you put a 55 Amp converter in series with a 100
All converters in series must be same make and model
NO.. The parallel pair,, Those too need to be identical to each other.> But need NOT be identical to the first pair.