X-240 Balancing Transformer

OK, so I have a 2 inverter setup (Outback Stacking Configuration) with the X-240 transformer set up as a balancing transformer for 120/240 split phase. Right now, the slave inverter sleeps most of the time (when the total load is 1000w or less) and the 240v is provided by the transformer.

However, I noticed that if I run a rather large 120v load on one leg (such as my compressor which draws 15amps and surges to at least 20 or my small mig welder), at some point the X-240 double-pole 20-amp output breaker will trip. It will do this even when the generator is feeding the inverter.

So I spoke to outback earlier and they said the breaker was tripping due to an imbalance greater than 20amps between the loads on the 2 legs (which I think makes sense). They offered 2 suggestions:

They think it is possible that the slave inverter is not waking up fast enough to handle the additional load, thus overloading the X240 due to the imbalance and tripping the breaker. They suggested turning off the power ranking on the slave inverter -- basically let it run all the time and never go to sleep.

The other option, that they have implemented in other systems and most commonly in larger systems, is to add additional X-240 transformers in parallel with the first and increasing the output breaker to a larger breaker. In this case I would have to add the external enclosed PSX-240 because there is no room for another X-240 inside the FW500 enclosure. Meaning I would then have a 45a DP breaker instead of the 20 (because the external transformer has a fan and is rated at 25a). Kind of an expensive $500 addition, but...

I have disabled the power ranking as a test and will try running the compressor again tomorrow, but then I started thinking...doesn't that defeat the purpose of having the X240 to begin with? If I was going to leave the other inverter on all the time, what benefit would I even have using the balancing transformer?

Your thoughts, comments, real-life experiences are welcomed.

Thanks,
Jay