The suggestions so far are right on
Lower your oven temp and make sure the strips are wet, but not dripping.
.........The strips are supposed to make the bake cook more evenly/level.........
The wet toweling will keep the sides of the pan cool while the heat of the oven will cause the cake to bake mostly from the bottom. That allows for a much more even distribution of heat so the cake does not form that hump in the middle. It also increases the moisture in the oven and allows for a moister baked cake
Don't worry one bit about them burning
I have for years used wet *paper towels*! (In a gas oven). When I posted this some time ago someone wrote that they tried it and the paper towel fell off and caught fire on the electric element. My feelings are: they didn't get the towel wet enough or adhere it to the pan. They must be *wet*. Then I take 2 fingers and go down the strip just enough to strip off the drips keeping them from dripping while attaching to the pan. Paper towels will stick when they are wet enough. It doesn't take much - just a light rub - to get them to stick to a pan when they are wet enough.
If you are still very worried you can wrap the wet strips in a bit of aluminum foil but that will stop the moisture in the oven - not the cooling of the sides of the pan.
For 25 yrs I have baked 12x18 sheet and up to 16" rounds w/o a heat core or even a flower nail - just wrapped w/toweling and later w/BES (Bake Even Strips - Wilton's name for their product - which is cotton enclosed in the same (silver) covering used on ironing boards).