I have used the Castleton crane several times and it is excellent. Last time I was there they charged $1/ ft of mast length, but they charged $1/ft of
boat length. Very relaxed, friendly people. You might be able to find the
wood to make supports for your mast 'behind the shed' there but it is better to bring your own
wood since you would need a car to get somewhere to buy it.
If you don't want to do it yourself, there are several
marinas with cranes eg the one mentioned.