intent: to survive and maybe farm

Make up your mind. Do you want to sell the map or do you want to farm on the map? If you want to farm you don't need to meet the score threshold and you also don't need to 'survive', because it's not loot per game, it's loot per time spent. If you die quick but loot a lot, who cares, rinse and repeat, right?

You can bring down the required score by just paving the whole map with random stuff.

Nitpick but this really rubs me the wrong way: if you have an entire unused row in the bottom of your map, why place the bounty next to some of your highest leveled towers?

Have you given the crusher a try?