Interesting challenge. Like you, I have an answer that fulfills the problem, but it's not particularly artistic or difficult. I'm going to try to come up with a better one, but for now - White to mate in three.
Another Challenge:
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lol, thats much better than mine, actually quite clever. Mine's a clutter of 10 white and 9 Black pieces.
Can we see it anyway? I thought it would be harder to do with more pieces.
OK
Interesting idea! So the point is that if c4, Rd4# doesn't block the Bishop? We both used completely different approaches, this is nice to see.
Does anybody else have a different way? I sort of have an idea, but I'm not sure how well it will work.
Yeah, but I dont really like this, Black has moves (like c4 or Nc7) that allow mate in 2. Yours is much better.
I think this is better than my first, but it's definitely a work in progress. It's really ugly with a lot of pieces splattered around simply to cover a2 again without creating another solution. I'll work on it later, but for now - White to mate in four. It's easy because you already know the key, but whatever:
Ah ha! This version feels much cleaner.
Nice!
I got this, using your concept of blocking g7:
The mating line is very nice here! I like how the Rook gets out of its little trap.
Does this count? 
White to move and mate in 3 maximummer
Yeah, it counts, I love maximummers
Probably easier than the 3 pawns one:
Compose a direct mate (mate in #) problem where the key move is 1 Ba1-h8.
I've been playing with this for a while, and have a working prototype, but it's not very elegant.