I've rigged my mainsheet with the cam by the boom and, at other times, with the cam at the traveler. At the boom, I have trouble reaching it to dump wind. On the floor, I sit with my foot on the sheet, which in keep taut on my leg, ready to stomp an release. Does this sound reasonable? How do others prepare for those pesky puffs?
You want the cam block on the traveler but the question is; which way do you want the rope to release from the cam, up or down? I have Schaeffer blocks and the cam can be removed and inverted so that when I pull up on the rope, it will release from the cam. You can have rope release by pulling down on the rope.
The cams on my main sheet and also my boom vang are held in place with two bolts and nuts.
You really shouldn't have to mess with the mainsheet unless your sailing in extreme gusty winds. Just use your tiller and head up a little in the gusts. It's a lot easier than letting off the mainsheet.
Most of the time, I sit on the Port side and steer. I'll stay sitting on the port side and head up a little in the puffs if they're not to strong and over bearing. If they get real strong, I'll sit on the high side and point up a little in the puffs. I'll reef the Gennie a little, if the winds get too strong, or just furl it and sail with the Main.
If your cams are removable like mine, you should use thread locking cement on the bolts and nuts.