proposal puzzle

I want a puzzle that consists of a grid of letters with a secret message hidden in it. The message is "will you marry me" possibly with a question mark too. so far, I like the idea of a grid of letters covered by some tiles. The letters on the grid would share a component with the letter in the message it corresponds to, e.g. a 'B' could be where an 'R' is meant to be. And the tile that covers this letter would cover the bottom of the 'B' in such a way that it looks like an 'R'.

I was thingking of a 2 by 8 grid where each letter takes up an equal space so that the grid is regular: e.g.
WILL _YOU
MARRY_ME
R V R Y T T D R
Z V B W R R M T

or a 4 by 5 grid
WILL_
__YOU
MARRY
_ME?_
Z V Y J W
W M Z D N
T N T R M
M J N R K

as examples.

Any ideas for the executing of this project or ideas for which letters are best to use is appreciated

What I need done is: a method for creating the puzzle on paper, a way to make it reality, a one off product that can be cherished.

Thank you for any help.

p.s. I have attached two files that I've made that helped me visualise some aspects.