Making an 80 ampere (continuous) 12 volt MOSFET relay (?)

Will the relay current be directional or bidirectional?

What is the maximum voltage that will be seen across the open terminals?

To get the resistance-drain-source (rds) down in the 20 milli-ohm range will require a few of these in parallel or rather expensive individual devices.

Are you switching resistive or inductive loads?

Sorry for all of the questions, but it makes it easier to walk through when the operating space is defined.