I have a Bearikade Weekender and a 2014 Arc Blast (52L), and while I can get the Weekender to fit, it’s really tight, so I’m not sure about adding to the circumference with padding (and your Scout is the same diameter). I have not had problems with fabric abrasion from the bear can, but I push the bottom of the can below the frame’s middle crossbar, which is where I think friction has the biggest potential to be a problem if you rest the bottom of the bear can on top of the middle frame bar, with the pack fabric sandwiched in between the two.
Bob, interesting suggestion on insulating the canister. I have found that with the tight fit in the Arc Blast, the wall of the canister is flush against the pack fabric, so when the sun hits it the can absorbs a lot of heat (as someone who started a week-long trek with a bunch of dark chocolate bars lining the inside of his bear canister, guess how I know). My cook kit includes some pieces of reflectix that when on the move I now put between the canister and the pack fabric on the side against the pack front (where the sun can hit it, I don’t need to block the sun from the side that faces my back). The extra thickness of the reflectix makes for an extremely tight fit and represents extending the canister’s diameter on only one side of the canister, so to the OP if you wanted to pad the canister with reflectix all the way around I think it would add too much to the diameter you are trying to squeeze in there.
And again, this is with a 2014 52L model, I don’t know if the pack body’s diameter is the same on yours, if it’s a little wider then padding the canister might fit inside. If not, you could try making a tyvek sheath for the bear canister, that would put a layer between your bear can and your pack’s DCF that certainly would fit and would weigh almost nothing (but would provide little if any insulating value).