Well each of those two amplifiers could take 8-12 Amps average
each ( manuals
Hifonics &
JL Audio) using 4Ω speakers in normal stereo (non-bridged) mode if the volume was turned up. However I would suggest that you might need to wild camp if doing that - I can't see you being allowed to stay long on a normal site at those power levels!!! If you actually run at high to normal listening levels in the van then you can could draw an average of around 8-10 Amps for the pair of them. The Processor is unlikely to take more than about 1 Amp. So I would suggest a load from those 3 devices of about 10 Amps if played loudly and I would estimate about 6 Amps if played at normal levels (to my mind that means you can't here it outside the van when standing about 1-2 metres away with the doors closed).
You will need to allow for lighting in the Van as well so probably another 1 amp will go that way, making about 7 amps whilst playing music.
If you have any LCD TV like displays then allow another 1 Amp each.
By the way the Hifonics alone can draw up to 55Amps peak so your 12 volt wiring to the amplifiers will need to be short and very hefty.