I can't find any way to improve it. (tweaks it another dozen times)
Party: 1 TB monk, 3 summoners with guardian pets (monk/huntress)
I cycle my tower boost right around 800-900 kills to ensure it's up when rush hits at the end. Alternately, wait until about 300-400 kills into the wave to activate TB and it should stay up through the end.
Working a cross fire arrangement in 6s, total of 18 towers.