Wilderness Lodge is curently served by 2 kinds of boats, small boats that are not accessible because they require a step down and larger boats that some call Motor Cruisers. They alternate trips and both stop At the same docks - the docks are labeled "Motor Launches".
Motor Cruisers are large boats that go to and from resorts at MK are usually accessible, but may not be if the water level is very high or very low (which doesn't happen often).
Boat captains have some interesting ways to overcome this if the difference is not too large. We have been on boats where all the other passengers were unloaded first; the almost empty boat floated higher in the water. That made the distance close enough that a small portable ramp could be used to get off the boat.
If there is too much difference in water level between the dock and boat, wheelchairs and
ECVs can't be driven on. They do provide alternate ways to get the the parks if this happens, usually extra buses.
There are no specific
ECV or wheelchair spaces on the boats, so no set number of how many can fit.