Hope you dont mind but here are a few more pics of it.
I dont think its too big at all but, looks to be a lot of trimming if all fences etc get done each time. The front fence is around 800m if doing each side. (Get a back pack trimmer)
Had a look on Streetview and man, I reckon that would be a fun place to mow! Most of the visible trees on SV dont require trimming!
I would break it into 2 half's and do each half over 2 days unless you have a crew on trimmers etc.
I would certainly want at least one helper on the trimmer.
As far as cost this is how I'd break it down. Not saying these are the numbers you should use but just a way of thinking of it...
What do you consider a decent daily wage? Add 20% for trimmer wage.
You have to buy a machine for it so I'd put on another $100/cut for that.
Lets say $500 is an ok days pay, then it would be $500x2+200+$100, x2=$2600/mth.
You could add fuel and contingency. Say another $100/mth.
Total then would be $2700/mth
As far as mowers go, I would certainly look at one that has suspension. The triangular paddock looks like it could be pretty rough. I would certainly look at the SuperZ (demo the cut). An SZ would smash that place out no problem. The nicer yards could be cut flat out, thats going to save a heap of time over most other machines!