I have many GBs including the Arc, Artic Orangery, Rainforest Project, Inno Tower...18 GBs in all and I am LMA. I had roughly 15 by HMA. I haven't spent any money on this game. Much like in life, it's all about who you know so they can help you out.
I really hate the extra attempts award as well. If I go all out on one encounter I expect to at least get some kind of reward instead of something that practically says "Hey good job, let's see you clear another encounter before we reward you!"
What if you could buy a temporary 2nd wave from the tavern? You could have 3 choices, the lowest having the lowest cost and least amount of troops while the higher priced option gives you more time plus more troops. The middle option would be somewhere in between.