I would use a momentary switch mounted to the stomp mechanism and a battery contactor.

Cole Hersey manufactures the momentary battery contactor that you mentioned, however I never could get them to last that long due to arc flashing of the contacts because the switch is not an over-center design that positively engages.

Your best bet is to use the standard starter, wire the S terminal to the B terminal on the starter then use a contactor like the White Rodgers 120 series that handle 200+ amps.

Then be creative and mount a simple momentary switch to pilot the contactor. The switch will need only a 5 amp contact rating

The problems we face today can not be addressed at the same level of intelligence we were at when we created them - Albert Einstein Or with the same level of $ - Me