It's a big lake so it might make a difference where you are on it. I'm in Moultonborough and couldn't get some of the companies to even come out to even talk to me.
I ended up using Lake Region Marine Construction
http://www.lakesregionmarine.com/ and would do so again in a heartbeat. Very upstanding and honest guys that stand by their work. They did a 40' tilt up aluminum dock for me. I live on a very windy point and had some issues with the wind moving it the first winter. It took some trial and error to figure out how to reinforce it sufficiently but they kept at and eventually figured it out. They are also the people that did the docks in Meredith a few years ago so it's pretty easy to check out their work. I would highly recommend them.