I haven't used PE sheet for an actual tent, but I have used rolls of it to make patterns for my tents.
Duct tape has a rubber adhesive, and this will creep. OK for quick repairs, but not for anything permanent.
Packaging tape comes in two varieties: cheap Chinese with a lousy adhesive which lets go, and expensive brand-name with a good adhesive. Brands like 3M, Husky, Nitto, Scotch should be fine. As it is a lot lighter than duct tape, try using a couple of layers.
However, really permanent-bonding anything to PE is hard to do without using really specialised adhesives which cost a LOT. Don't bother.