the whole purpose of wrapping is to stop the spring from grinding away at the material of the stanchion,a deff no-go on the sleeve it would add useless weight and restrict what travel you do have.a sleeve would make it bind up more and possibly damage those forks you finally tuned for yourself.
but the sprign is firmly in place and is not grinding anyhting, as for the diameter of the inside of the spring and the diameter of the rod it is around, i fitted two spacer/shims so that it does not move side to side so everyhting is all good in that compartment, get me ?
ohh man i didn't think of that, i used this wired thing around some of it to keep it together and seems its worked, its in my 80mm fork, locks out at 35mm down approx, i love it like that as i dnt like the whole use of suspension just enough to take the harsh landings on the front wheel so i dnt get wrist shock
yeah if you shrink wrap it then the sharp edges from cutting it will be covered and it wont wear down the stanchions and contaminate your oil and foul your valves.