My Livescope tdx & Hook 7 tdx never have the same temp reading. They're usually off by 2-3deg from each other. Both are on the trolling motor, and about 1ft apart.

I rarely pay attention to the temp diffs between them and just figure the real temp is somewhere between the two.

I'm curious as to why you think you need a (near) 100% accuracy in the surface temp ?? Like Rickie says, "that" temp is not necessarily the temp where the fish are .... which could be a few degrees to quite a few degrees different, depending on depth of the fish, than what you're reading close to the surface.