Well, I've shot shows at Fort Canning before so there's gonna be loads of people on a grass slope and if the ground is wet you got to watch your step. It can get quite slippery.
I know that they said that photography is allowed but are you really sure you can bring in slrs with long lens?
The only way you can get decent shots is going super early, stand right in front, not lose your place and battle the heat and sweaty bodies around you.
Or of course, you're one of the official photogs with media passes.