SCR for load bank switching?
I could do it with contactors but would like to use an SCR with a pot
  and allow the current to be ramped up with the pot. Any thoughts?


It's a foolish idea for at least two reasons: -


An SCR will latch once conducting and stay latched hence to disconnect the "load bank" from the battery you will need a contactor. Of course it makes sense to just use the contactor for full functionality.
Current won't ramp up with either a contactor or an SCR with or without a pot. If you require a variable load impedance then use something else that can be controlled on/off in a PWM manner. I'm thinking banks of MOSFETs and an inductor here.


There will be kilowatts of heat to get rid of so design your load bank rig carefully.