I have similar HAM radio plans -
My Medic-Master / Freightliner will also serve as a "Communications Facility" for the USCG Auxiliary, and will be capable of supporting field communications as ordered. Equipment will be set up when required, with custom mounting brackets and power taps. Since it has a 270 amp alternator, power is not a concern. The roof has 5 NMO antenna mounts and one scanner antenna mount, with all the leads routed to the existing radio cabinet. They will be terminated at a bulkhead panel so radios can be easily connected. The existing siren has been blocked to just the radio position, with PA over ride. Something like a Kenwood TM-281A (for HAM frequencies) and a TAIT 2020 (for USCG communications) will probably be installed in the action area panel, and possible something similar with a Havis mount in the cab's console.
The vehicle will a 4 kW Onan generator, and will be capable of complete operation from a separate generator.