Then again, there are wireless HDMI extenders. If nothing else, a small investment to test and see if they will work.
Here is one sample
product via Amazon.
My first inclination, having thought about similar options myself:
Field transmission kit:
1 motor cycle/rv type 12v battery (deep cycle)
1 400w (or appropriate) inverter
1 power strip
1 hdmi wireless extender transmitter
1 hdmi cable (ST16 to HDMI transmitter) - adequate length to stay out of trouble but not trip if pilot is one who tends to wander.
Field receiver kit (basically same as transmission kit):
1 deep cycle batter
1 power inverter (enough wattage to drive monitor and hdmi converter (400w-800w should do it)
1 power strip
1 hdmi wireless extender receiver
1 hdmi cable
1 monitor - of course, the larger the monitor, the greater the power source need!
One would think that should do it, at a minimum anyway.
Jeff