Both portages are relatively flat, tho the Black Robe can have some shallow mud. Both have some rocks and roots, which would not be easy in a wheelchair. Minn has always been a 'pass through' lake for me, though I have heard that it has some decent bass fishing. Not knowing any more than what you posted, I would have questions regarding egress from chair to/from canoe, what happens if there is a capsize, sanitation issues, just to name a few. Probably you have thought through these issues and have some level of comfort with them. I guess it boils down to thinking through all of the possible 'what if' scenarios and having a game plan to deal with whatever issues may come up. We wish you well.