What I'm suggesting means you can still have a 16x16 grid to store additionaly information -- such as the author and player starting coordinates -- Basically, the -1 values wouldn't be recognized as a piece, so the spaces with -1 as the value wouldn't have any tiles. There would still be plenty of space for author name and starting coordinates. Example array to illustrate the point:
2222222222222BBB
2111111111112BBB
2111111111112BBB
2111111111112BBB
2111111111112BBB
2111111111112BBB
2111111111112BBB
2111111111112BBB
2111111111112BBB
2111111111112BBB
2111111111112BBB
2111111111112BBB
2222222222222BBB
BBBBBBBBBBBBBBBB
BBBBBBBBBBBBBBBB
BBBBBBBBBBBBBBAP
2 = Wall
1 = Grass
B = Blank space, represented by -1
A = Represents author name
P = Starting player Coordinates
I hope that better illustrates the idea behind it.
So the "B"s won't be recognized in the For each elements...
But the A and P will always be counted, and those aren't part of the gameplay