I find duct tape too sticky tbh so i would suggest electrical tape. Thats what i use if i need to tape directions to my tankk.
Also its how you lift the tankbag off that causes the scratches to the tank. Just remember that lots of small grit particles get in under the magnetic flaps so make sure you lift the flpas off the tank before lifting the bag off the tank.
oh and wipe em off before you refit the bag. Even if you have tape down its good practice.
Just dont do what i di and get carried away worrying about all that...and forget to do up the strap at the front. getting a face full of tankbag at 50mph and trying to get it back down one handed aint fun!
i'm sure it was funny for anyone who was at the bus stop i was flying past at the time and saw it happen tho
me.