This is a fairly standard set of specifications for a Great Lakes lighthouse tower and detached dwelling built under the Pleasonton administration. I have specifications for other lighthouses built under his administration which are virtual duplicates.
I have attached my transcription of the 1829 specifications for construction of the lighthouse at Tibbetts Point near Cape Vincent on Lake Ontario. I believe you will find them to be surprisingly similar.
The use of written specifications lead to numerous interpretations on behalf of the contractors hired to build the lighthouses, some of which significantly compromised the durability of the structures. This problem was exacerbated under the Pleasonton administration in that responsibility for lighthouses in the field was delegated to the local Collector of Customs, a group of Bean Counters with absolutely no engineering or construction experience. Yet, these men were responsible for not only for compiling the specifications and selecting the contractors, but also for inspecting the lighthouse on completion and determining whether it met the specifications, or not. No wonder virtually no Pleasonton era towers are still standing!
As it happens, I wrote an article on the tall and narrow lantern of the Bailey's Harbor lighthouse in the fall issue of the GLLKA Beacon which makes reference to the use of specifications as opposed to prints, of which I have attached a PDF copy since you might find it of interest.
In reviewing the South Manitou tower height in early Light Lists, it appears that my original assumptions as to the appearance of the original lighthouse were incorrect. I would now conclude that it likely took the form of the rubble stone tower and detached dwelling outlined in these specifications you received from Candace Clifford until it was replaced by the cream city brick and integrated dwelling and roof-top tower in 1858.
The replacement structure erected in 1858 was built by the Lighthouse Board, which as I am sure you know, was formed in 1852 in reaction to the shoddy situation in which US lighthouse found themselves as a result of Pleasonton's administration. The Board was made up of scholars, engineers, scientists and Navy men, with the requisite base of knowledge and experience for the task at hand. In turn, the country was divided into a number of districts, with each district staffed with a West Point graduate engineer to manage the physical aspects of the district, and a Navy man to manage the human resources and administrative aspects. As such, a set of bona-fide plans would have likely been drawn-up under the supervision of the District Engineer for the structure, which would then have been passed on to Washington for final approval.
Documenting history is a wonderful thing - one has to go with what one has until improved evidence surfaces.
I hope this helps answer your questions.
Thank you for sharing this information with me. I would greatly appreciate receiving anything you might wish to share at any time. The more we know, the better we can interpret the past.