Most of the field trips on Sunday are wheelchair accessible- some better than others.
The Peace River trip may be most problematic because, although parking is close to the river, there is a high bank that will prevent access to river- no dock area.
The Emerson Point trip is easily accessible until you get to the temple mound which, although there is a boardwalk, has a fairly steep incline- not too easy if wheelchair is pushed although I've been told those electric scooter chairs can do it relatively well.
The canoe trip dock is wheelchair accessible although getting into the canoe itself may be a bit challenging but I think it is do-able with some extra hands to steady the canoe.
The Green tour of the HCC SS is most accessible with gently sloping access points and elevators.
Hope that helps you decide :o)
Looking forward to a great weekend!