One really good spot in Sidewinder is by the Pistol spawn (the upper level that sort of separates the 2 bases by the tunnels). There are 4 ledges (2 on each side).
An easy way to get up on them is by grabbing the FRG and OS (maybe camo too). Also might want to bring a few spare grenades in case you fail to make it.
Just throw a frag, and then shoot the FRG. Make sure you still have a good amount of OS (at least with it mostly in the green).
The spot gives you a great view of either of the bases, and you can protect the tunnels.
Heck, you could also get to the top of the map. Just bring some plasmas, a frag, and a rocket launcher.
Just position the warthog against one of the slanted walls by the plasma grenade spawn (in the tunnels), have the back of the warthog sort of facing the big hole in the ceiling. Just make sure you get the overshield right by the warthog. PFR (Plasma, frag, rocket), and try to grab the overshield and jump on the warthog just before the nades and rocket send the hog flying.
If the hog does launch you up the hole, you should make it (only concerns are landing safely).
Note: You may end up on the little ledge inside the hole. I don't know if it will be easy to get to the top from there. So maybe have an FRG instead of a rocket launcher.
Hope this helps.