Re: reducing draft depth ?
it depends on the boat, and the doing so should not be taken lightly. Some boats are easy...they were designed with a shoal draft and a deep keel, just swap one for the other. Other boats, the design and structure of the keel are paramount to the performance of the boat, as well as the safety.
If you can discover which boat and what you want to do, an engineer/builder of the boat in question can help with the project. Not cheap either way. A reputable shop is of utmost importance after the engineering is complete.
Others will chime in, I am sure.