[hiccup]

I do not think removing that panel will be in any way easy, possibly approaching completely unrealistic. I'd try to remove the inverter without removing the panel. It's jammed in there but looks doable, although may require removing a lot of other wiring that is in the way.

I understand the logic of adding a dc-dc charger but that is not a good idea. The inverter/charger units are designed to have a direct connection between the batteries and the unit. The input and output terminals of the inverter are one in the same. The batteries need to be directly connected to these terminals. I would look around for another place to mount the inverter as it looks like it will be tight. I'm not saying there will be a better spot but I would look carefully and consider all options.

The typical inverter install from the Tiara factory was an inverter/charger that charged the house bank and a second charger (the Charles) to charge the engine bank. You will want to stick with that arrangement. You might consider moving the engine bank charger to a different spot to make more room for the inverter/charger. There are really small and sealed chargers these days that are suitable for installation in the engine room. Make sure it is ignition protected if you have gas motors.