We have the emergency start switch as well, but I understand the thin guage wiring & solenoid cannot handle the amperage for a real "Jump Start". You need to hold the switch for a long time in hopes the dead battery is taking the charge properly.
So....
Just in case the dead battery doesn't hold a charge, I carry extra long jumper cables that reach from the chassis battery to the house batteries. So far I've used them only to help other campers.