Integrated RV HVAC system with hydronic heating and 12V A/C

I’m new to the forum and plan to order a Transit Cargo van, 144” wheel base, dual rear wheels, high roof, extended/long body, AWD and convert it to a class B RV. I've spent the last 2 months on this to develop requirements and come up with a conceptual design of the system. For the HVAC system, I plan to run a hydronic heater and an under van mounted 12V compressor & condenser for HVAC use with a rear heater/A-C unit (not coupled with the vehicle) when not driving. The heater would also provide hot water through a heat exchanger. The compressor would be powered by a 600 AH 12 volt lithium battery bank and about 800W of solar on the roof. Don't really want to put AC on the roof. Has anyone on this forum already done this on a Transit? Any suggestions or advice? I am really lacking geometric information of the underside of the van to place the A/C components - and tanks for that matter. There is a separate topic for tank placement that I have started to sort through.