"If you buy one with a center off position, it will just like the one FF uses"
Presumably then you could also add your own speed controller as well.
https://www.ebay.ca/itm/DC-12-40V-10A-PWM-Motor-Speed-Control-Switch-Controller-Volt-Regulator-QP/254347852877?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D2%26asc%3D20160908110712%26meid%3Df908c075ed794b128a4f7a9dfee6c9ca%26pid%3D100677%26rk%3D4%26rkt%3D30%26sd%3D323886635244%26itm%3D254347852877%26pmt%3D1%26noa%3D0%26pg%3D2385738&_trksid=p2385738.c100677.m4598