EV Camper - charging / battery / inverter

I would like to replication what Glyn did with his eNV200.

Looking for help and advice, van is ordered but I have no measurements or specifications

I'm finding an all electric EV setup interesting in terms of rethinking the norms of power charging and consumption. For example, since we need to recharge the main battery when travelling we can also charge devices / cook at the same time. The "leisure" battery maybe does not need to have the same capacity than in a traditional van because the DC-DC charger can top-up when the van is turned on, and no driving needs to be done (unlike alternator).

Requirements:

• Heating and AC during night
• 12V Aux battery supplies 12V DC power and 240V via inverter (Phoenix 1200W)
• Solar panel charges 12V Aux battery (thinking 400W panel)
• Mains hook-up allows charging and 240V power overnight if available
• Support 2 x 800W Induction hobs (all electric install) (assume no max power since 800W + 800W > 1200W)

Questions:

• Can OEM battery support inverter draw?
• Will solar panels support Fridge consumpion during the day?
• Is there a limit to the DC-DC built in charging provided from the Van?
• Could the DC-DC charger support induction hob cooking for 20 mins (for example), how do I measure the DC-DC charge rate? Smart shunt?

Current thoughts:

• Upgrade 12V aux battery. Not sure whether AGM or LiFePO4? Max physical dimensions? Minimum capacity?
• No point having Multiplus, since van has built in DC-DC charger. Hoping solar will charge battery during day and support daily consumption.
• Need to split shore power to van charger and 240V circuits, so it's not going through the battery (inverter) when not needed
• Cooking may only be possible when at charging station or on camping hook-up. Depending on above