My suggestion and what we have suggested in the past is to take the prop off of the larger motor. As long as you are only running the trolling motor on that rig you will be fine, just be ready for the onslaught of people thinking you're running the other motor.

Sec. 15-121-B15h. West Hill Pond special regulation
On the waters of West Hill Pond located in the towns of New Hartford and Barkhamsted the following restrictions shall apply:
(a) No person shall operate or allow the operation of a motorboat equipped with a motor or motors with a total greater than eight horsepower from Memorial Day through the fifteenth of September, both days inclusive. For purposes of this subsection,
Memorial Day shall be as defined in section 1-4 of the Connecticut General Statutes.
(b) No person shall operate or allow the operation of a motorboat at a speed in excess of fifteen miles per hour.
(c) No person shall operate or allow the operation of a motorboat at a speed in excess of six miles per hour between sunset and sunrise.
(d) No person shall water-ski or operate a vessel towing a water-skier.