Generally, with good organisation, and if things go fairly smooth along the way, you should have no problems getting married within a 20-30 day timeframe.

My advice is to get everything lined up well before hand.
Get as many of the docs and paperworks done before you actually arrive into the Philippines. It's not difficult.

An alternative would be to take a shorter trip and secure the marriage Licence and return home, then make another shorter trip to actually get married and honeymoon.
Some folks have done this when getting longer periods of time off from work is problematic.
The Marriage Licence has 120 day validity anywhere within the Philippines. jusy food for thought anyway.