Check out the Adirondack Trail Ride route for ideas:
http://www.theadirondacktrailride.com/the-route/It's about a 3-hour-ish drive from Ottawa to the Lake Placid area. Resupply locations are on the page I linked you to, but I don't know if they are 2 days' riding apart. Your April itinerary may be the biggest problem if you want to ride off-road, as everything within 6 hours of here might still have snow, or at least be really soggy...
Cheers,
Kim