Place west side auras just outside the hollow tree entrance, so it hits the lane below as well as the crystal barely. The gas trap should be as far inside the tree and to the east as possible to make sure the bottom lane isn't hindered too much. Place the west physical beam as close to the tree as possible, it's no issue if the beam doesn't quite reach the other side. This way, ogres cannot hop over the little ledge next to the tree, also the beam will be angled up, making it harder to jump over for them whenever they pile up. The north beam doesn't have to be 4 DU but there's 1 DU left over. 

Upgrade towers wave 32 with whatever you like and have your tower booster on split (not needed if you don't want, just have to flash heal the wall occasionally).

On the last 3 waves, place a guardian summoner on LTs and have a tb firing either out west or up north. Make sure to boost the west web wall for faster kills. Can build the spider with your guardian summoner.

For the last wave, add 2 wheel jesters if you wanna speed it up or just an extra boost summoners + builder app if you feel lazy. 

Most important stats are aura range and apprentice in general. May struggle a bit at lower stats than 7-8k. May want to add more web walls on the left side and a gas trap if need be and remove an LT.

Another variant for even less building (pretty much same time) is to remove the web wall, the seed bomber and reduce the physical beam on the north side to be 3DU and add an 8th lightning tower instead. If you do this, make sure to have spiders on both sides. 

In addition, you could build on split if you build in wave and then remove that split to set mob hp back down to 1 player scaling. All up to you. Or just start combat with 1p.

Vid of a run for placements and proceedure: https://youtu.be/2uzr2JcwNE8