Board Thread:Questions and Answers/@comment-7308185-20130506192008/@comment-3153244-20130509100139

Towers were placed as soon as they were "unlocked", excluding the Ice Tower, which I ignored. The Monkey Ace should have the horizontal 8 path.

Order of upgrades that I used:
 * Dart Monkey 2/3 (target last)
 * Tack Shooter 3/2
 * Bomb Tower 3/2 (target last)
 * Apprentice 1/2 (target last)
 * Village 1/0 (upgrade optional)
 * Farm 2/0
 * Engineer 2/1
 * Bloonchipper 3/2 (target strong)
 * Boomerang 3/0
 * Spactory 1/2
 * Ninja 2/1 (Get 2/1 ASAP during Round 42)
 * Apprentice 2/2
 * Engineer 2/2
 * Super Monkey 1/0
 * Ninja 3/1
 * Super Monkey 2/0 (ASAP during Round 49), followed by 2/2 during Round 50
 * (optional) Engineer 2/3

Image of tower positions (since the game ended before I could take a screenshot, I have reproduced as close as possible my setup in Sandbox.)