I can recommend the “eastern” route South - (Oswego to) Erie Canals, Hudson River, outside to I.C.W & southwards ...
It’s a splendid tour, and a fairly easy route.
You’ve a particularly large boat, which will present a few minor (or not so?) challenges, no matter which inside route you take:
1. The canals have a 10 Ft bridge clearance. Can you clear 10' with the mast
lashed horizontally on/above deck
? There are facilities to de-mast at Oswego (& I presume Buffalo etc) and free materials to build your mast-storage “crutch”. Don't know about Chicago.
2. Boat handling in tight quarters can get interesting - but then you are an experienced power boater.
is always a problem /w larger boats. Over 6' gets problematic on the I.C.W.
I'd also reconsider a late season departure (which could be unwise on any route). If it's too late to go "outside", it may be (just plain) too late, period.
For what it's worth ...