Build works great and we ended up going way under DU cap so that we can boost both stacks with the guardian pets.  If you have ideas for the 20 DU, go for it.  Why are we under?  To boost the towers and the auras, so we stayed at 6 towers total per stack.  Things we could add: Pylons, traps maybe...IDK, it works well at present, but if you find something to accelerate it, let me know.

Timer is super short.  Wave 1, get the auras and buff beams up, build 1 nest at each spot. This is enough to beat the wave.  Place a summoner at each one.  In combat collect mana and build the rest.  Quick swap to app for the LT up North, then back to guardian.  Keep guardian in and use upper to up everything, no TB in the group until the final wave.

Party: 1 Builder Guardian, 2 summoners with monk/huntress pets, 1 upper (final wave swap in TB monk)

Right now, 7:42 total time.