have you actually tried to start the w/m on the inverter or just believe it won't do it as per spex ?
i ask as we have started and run our w/m (80LPH echotec) on our inverter, even though the spex suggest it wouldn't do the start up
inverter is 4000w with 6000w surge capacity
of course once it's going it drains the
batteries super fast, but it will start & run
cheers,