Plenty of forest, but relatively little forest away from well marked trails, urban developments and authorities that don't think people should be living in forests.

Go look at Singapore on Google maps. There doesn't seem to be much, and all of it has marked trails. Are you sure there's "tons"? I admit I thought it had much more.

Had a big green snake in downstairs in the garden.

Singapore has very little primary forest left, it was almost all cut down for plantations in the British colonial era. But since independence they're done a pretty decent job of reforesting, and in the tropics it doesn't take long at all to go from a field back to an impenetrable jungle.

I assume your are referring to the land used by the military?