are the genii of batteries in the UK
I dont know if they have a gH2 solution but can certainly build leads that regulate power
Vlock runs my video kit, with some bits can run off lighter 'Z1 batteries'
Hawkwoods have made this happen..
If I were you I would pick a battery system, 'Z1' or Vlock and try and run everything from that source
Vlock have the welly to run multiple items (camera monitor, sound recorder, follow focus motor) from one battery, while z1 batt need 1 batt per Item typically..