What worked for me is just spamming Smartbug launchers with an extra heart perk. Since the enemy queen has no flying units he dies easily.
Also yeah, goop slugs + tanks doesn't seem to work well as a strategy.

Goop slugs + tanks is very effective against weak units, the scorpion is just too strong so they tear your tanks apart. I won this level by spamming sky queens and mini-bombers, it's an overall good strategy on any level you have both.

thx

I beat this level on hard by building skitterbugs and mini-bombers in abundance.