I want to use the Multiplus II x2 to handle both legs of my US based 120v boat's AC/charging/inverter needs, HOWEVER it is 3" taller than my available space to mount it, so I need an alternative. If I use the 230v version of the Multiplus 12/3000/120 (which WILL fit in my space) will that do basically the same thing for me? What if anything do I give up or gain with this option? Any insight or advice would be appreciated!
No that will not work unless you also install an auto transformer. (Even with an auto transformer you cannot change the frequency, only voltages) US is split phase where each 120 leg is basically half of the full single phase 240 with center tapped neutral, and at 60hz (a very basic explanation which may not be entirely accurate, but you get the idea). EU is typically 230 single phase with no center tap neutral at 50hz, or 3 phase where each phase can be 230 or other variations. The two are not directly interchangeable. (I'm in the US so admittedly know very little about EU power but enough to know the answer to your question is no)
Whether using dual 30a 120hz shorepower or a 50a-240hz shorepower, if you can’t fit the MP 2x120, a good configuration is to use 2 Multiplus’s in split phase. These are much shorter and have more peak power (read: you probably won’t need a soft start for the 16k btu aircon).
It allows for each 120v leg to have 2400W continuous while on the hook vs the 2x120 will share its 2400W across L1 and L2
Of course, instead of height being the challenge, you may run into width as the conundrum. Good luck.
