Jeff, you might be better off trying to do a "lease back" or "buy back" arrrangement with one of the charter companies, where you would undertake to buy a boat outright, with them guaranteeing to repurchase it from you when the period was over. Or, for you to lease
it outright for the period, etc.
I'm sure they'd give you a better charter price
for 14 weeks but that's not their normal business, and if they ARE any kind of success at their work--they would take a loss by giving you any kind of substantial break.
Many people have asked the same question in many places, but I've never heard from anyone who found a place to do long term charters per se.
Once you add in "the Canal" things will get way more complicated, that's going to be totally outside their normal insured sailing areas, and you'll need to look into the paperwork to bring the boat into the US as well, regardless of who the owner is.
Then of course there's the matter of getting the back BACK to where it came from. A major expense, unless you're planning to sail the Canal twice.