Is it possible to use two different inverters on the same offgrid system?

[Yup]

Crazy thought from fantasy land... would something like this work to minimize idle draw? Hook up both inverters independently to the same battery and set the larger one to ECO mode with a high threshold (assuming it is programmable). Most of the time, the load will be too small to trigger it. If you kick in a heavy load, the larger inverter would drop out of ECO mode, and for a time, both inverters would draw power from the batteries and supply it to the load. If the load gets too high for the smaller inverter, it's overload protection would kick in, and the larger inverter would handle the load alone. After the load drops back down to normal levels, the smaller inverter would kick back in and the larger one would go back into ECO mode.

Is something like that possible?

I was thinking of doing this as well--making the Multiplus the main inverter and having the EG4 6k turn on automatically when the load gets heavier. I saw the Off Grid Garage's video of configuring a Multiplus and Phoenix inverters the same way but I need to sit down and read up on all the Multiplus settings to see if I can do it with my setup...I'm still new with all of this and just got everything temporarily set up last night.

One thing I noticed is the high idle consumption on that EG4 6000ex is no joke! It's also really loud compared to the Multiplus, which I had to check a couple of times to make sure it was still on. Even when charging the batteries on standby mode, the EG4's fans are so loud you can tell its running. That being said, I'd rather not have it running if not necessary.

For my set up, I have decided to put both inverters on the same battery bank but will operate them separate from each other. The Multiplus will be the main inverter running everyday loads. Since I don't have any other solar charge controller, I'll be keeping the EG4 on standby mode where it will turn on automatically only when the solar panels are producing energy--I don't know if this is typical of most AIO inverters but thought it was a nice feature. I'll also be using the EG4 separately when running heavier loads, L2 EV charging, dryer, etc.

Thanks for everyone's input. I still have a lot to learn and will try to see if there are any better ways to optimize my setup eventually.