1) Don't slide your canister light all the way to the backplate if you want to reach your butt ring... gaak... hindermost ring. Leave enough room that your arm can fit between the backplate and the canister light. You're welcome.
2) Yes... by all means slide a buckle onto the webbing and clamp it down to hold the light in place so that when you undo your waist strap the canister doesn't slide off into the water or onto the pavement.
3) Trim excess weight belting with a hot knife. If you don't own a hot knife just heat the tip of one of your steak knives over the stove until it is dull red.
4) Stitch the extra weight belt material into a knife sheath. Bust the tip off the steak knife from step 3, put it in the sheath and your in business.
5) If you gain so much weight that your harness no longer fits consider the $12~$15 new webbing will cost a penalty for being a glutton. That might save you from continued gluttony which would result in a $1500~$2000 penalty for a new drysuit.
