I think the reason your struggling to find answers to your question is simply no one knows anything about it as is the way with many vintage boats, i myself recently bought a 1960's cruiser and the only info i really have is the advert that came with the boat when it was originally made, Now it could be either no one knows or those that those who do may be of and age where they no longer do the hobby or sadly lost along with there knowledge.
However there may be hope yet...
Now i have no clue about this boat , I've been googling at it for a few hours now and no luck.. but the closet i got to something that resembles the hulls shape is the Bluebird of Chelsea, the hull is of the right shape, however its not steam driven...
There have been in the past many many steam launches and Steam driven 'Gentleman yacht' which at the time would have had a steam engine, i have a feeling it is most likely a gentleman yacht based off the Bluebirds hull,(it was popular during the period) this would have a large forward cabin , engine exposed mid ship with possible a canopy over the boiler, and a rear cabin or open deck aft with seating.
Have a look at the photo's of the bluebird and Mimosa & compare the hull for yourself, you may be able to construct the hull from her plans and a cabin section from images of other launches, or a modification of the bluebirds cabin mid ship.
http://www.myhobbystore.co.uk/product/18083/bluebird-of-chelsea-hull-hulbm1449That's the best i can do to help you get somewhere. Even if its not right the bluebird is a beautiful model built, and wouldn't be a waste of time constructing one.