I liked Parson's plan as well, that's why I was so annoyed when it unraveled so throroughly! But ground units don't have the range of air units. For a flying unit to have a range near 56 or 22, a ground unit sould have a range of 5-7 for "fast" units and 3-5 for "slow" units. Assuming the Woodsy Elves to be fast units and Gumps to be slow, Parson could have hidden the A-dwagons in the woods near the lake. Not over the lake, and slightly further "away" from the Donut of Doom. Ansom used the bats (as Parson predicted) for the search, so as not to waste the other unit's move points on a search effort.
Once Ansom fell for the "con" that was the Donut of Doom, Ansom's boops were in a vice that would be very expensive for him to escape. Either he loses a bunch of bats (primary scouting units), or he loses the troops he took with him, AND the confidence of his remaining troops, if and when he returns.
Jillian coming to the rescue would have reduced that cost by an appreciable margin, but now? "All hail the Conquering Heroes! Hurray for Ansom the Handsome! Hurray for Princess Jillain! Hurray for Count Doombats! They crushed the enemy's main weapon with only the loss of seven bats and a gwiffin!"
Cheese. Pure cheese.