question

Unless you don’t have any 12V loads you’ll still need a way to power those.

If you have the money to spare, id suggest the quattro route, as it is "better" in any regard. As kogir said, if you have 12V loads, you will need to provide a 12v bus. Easily done with dc-dc converters.

Main benefits are also that the cabling needed for the amount of power is much easier to handle. As mentioned charge times are much improved.

The 5KVA Quattro 24 volt has a max charge current of 120 amps which is easily done with a 15 amp 120 volt service so if that is the reason for a "panel" upgrade then it probably is not necessary.

The relays in the Multi will handle 50 amps so that's not an issue either.

Keep in mind, the Multi will regulate charging current based on a set AC input current limit so when loads get high, charging current backs off. But a 50 amp 120 volt service would allow you to run more devices and charge at the same time.

In the US, 30 amp RV power is 120 volt and 50 amp is 120/240 volt split phase (2 legs) so you'd need a substantial rewire and possibly two Multis/Quatros to handle the second leg. Your generator may or may not be capable of 120/240 split phase output. Of course, you could use just one leg of a 120/240 volt split phase service.

You need to decide if the additional inverter power is required which depends on the AC loads you plan to run simultaneously off the inverter. Soft start units on the air conditioner(s) helps significantly.

The Quattros have a second AC input making generator integration much easier and more complete. The Quattro (or a GX device) can control the generator based on shore power availability, battery SOC, AC load, etc. That alone may be justification for the Quattro.