I used the technic from MmM GHOSTFACE solution (aka go to the far left and stay there) but instead I use a combination of precision riffle and chainsaw.
You will see that each time an enemy comes across a certain limit I switch to chainsaw.
Another key element is to keep calm and control when the zombie deers come because you will then have to switch to arrows (which are more efficient) and of course avoid their ram!
Also if you use my video, try to avoid the confusing start. You will see a soon as you leave the left corner you cannot keep up because they are coming from everywhere.
The left corner assure you only have a small angle.