"Faint heart never won a fair maid"

I understand not basing an entire boat on a concept, but this would be a very cheap test.

Here is an article about making paperweights with leaves - not the same thing.
http://resincrafts.blogspot.com/2011/11/fresh-out-of-mold-shells-and-leaves.html

Everything I saw said make sure to press the leaves between the pages of a book for 2 weeks or longer to remove any moisture.

Nick's website once talked about printing pictures on "rice paper" then laminating the paper to the boat. Anything with no ink just disappeared.
Perhaps you could use the rice paper to press down the leave on the surface of the boat before you put the glass on.
Or use a really thing coating of glass fabric or matt to do the same thing.