Been on those boats in an ECV several times. Those are the same boats that take you from International Gateway to BW to BC/YC to Swan/Dolphin to DHS and reverse.
They have always had ramps available. We first used those boats either a wheelchair more than 20 years ago.
The waterways at Epcot are different than the large lake by MK.
The lake is very large and doesn't have a lot of ability to regulate the water level. There are a lot of questions interconnected waterways in the Epcot area, which does allow a little more adjustment.