I think it's a great idea. Since you will each have a child in a trailer, and will need to carry along supplies such as first aid kit, repair kit, water, weather protection for each day, swim wear and towels, spare clothes for the kids...I don't think you'll have much room left for your other gear...such as your change of clothes, toiletries, etc. so you would benefit from using a transport service for that gear...one that you could call and get a ride from if you had trouble reaching your destination at the end of each day.
Last summer I stayed for almost a month at a B&B on Le P'tite Train du Nord, a bike trail north of Monreal in the Ste. Laurentians. Once or twice, a couple would call around 10 p.m. and wonder if the host/hostess could fetch them. (They couldn't because they didn't have bike racks on their vehicle and at any rate weren't licensed for taxi services...the best they could do was let them off the hook for the reservation...they didn't have to do that but were kind-hearted...and try to recommend a place that might have rooms)...unfortunately, this is what happens when you haven't arranged with a transport service in advance...)
The other option is to plan on only a few miles each day but that would probably be pricier than transport service and it commits you to biking even in the worst weather to get to the next reserved destination. If you plan to camp, that's good too, but even campsites require reservations...if you're lucky then that trail will have general group campsites that don't. If you have 2 vehicles then you can work out a leap-frog system where in the morning then you all drive to the next location and leave a vehicle, then drive back to the starting point, pedal to your next destination, and then go back and fetch the vehicle you left at the start. It sounds worse than it is - remember you can drive in 20 minutes what it might take all day to pedal with hills and stops for activities with the kids! This is the method I had worked out in my mind for doing a bike trail with a good friend.
Now, everyone I met at the B&B who was biking looked like they were having a terrific time.
I live over close to Portsmouth, sometimes I head over towards Newbury, near Lake Sunapee...if you want to get together and bike with the kids in the spring, for training, we could figure something out between my Burley, my Rhode Gear seat and my Trail-R-bike...maybe we could put the little ones in the Burley and you could ride with your 5 year old with the Trail-R-bike. There are some nice bike paths I know of around here to ride on...do you have a road bike or a mountain bike? I have a decent bike rack on my car, too : ) I used to ride with two prechoolers in my Burley...I used to have strong legs, too! On hills! I don't know what I'm capable of now...since I moved I haven't really been biking all that much because it's required going in the car to get to the safe roads : ( But I WILL now that my 'baby' can sit up in the Burley and have more fun if I put him in the seat on the rack.
ooooo, I am so envious. I so wanted to do the trail up in Quebec this summer, but it's not in the cards for me : ( I may bring my bike & trailer up there though and do a part of it.