In this situation money talks and the best thing to do is contact a judge directly and negotiate a fee for marrying you on your preferred date, He/She will charge you much more than the standard fee, but whoever performs the marriage ceremony, they will charge much more when they find out a foriegner is involved anyway. If you know anyone who knows a judge there in CDO it would be better to contact the judge through someone else rather than at the courthouse where other palms may also have to be greased. As I say, it will be much more expensive, P5,000 or maybe even P10,000, but at least your in control of the situation.
By the way, try to do a deal whereby you pay the judge so much up front and the rest when he turns up to perform the nuptials.
Iain.