I don't think it is up to skeptics to disprove something like this. It is up to you as a believer of something that has never been proven to get hard evidence of your theory. It seams like you have already made up your mind and will not accept anything to the contrary.
As far fetched as it would be, i would believe that these tracks are made by a one legged kangaroo that escaped from someones house before i believe the bigfoot theory, if only because i know that kangaroos exist.
You have a large burden of proof to supply before you can claim that some slightly strange melted track are made by a large beast that has never been definitively proven to exist.