In my experience the Dev con shouldnt be used on plastic bait repaints. It seems to crack and chip off very quickly. Not sure why but Im not the only builder that has this opinion. Its good stuff, just not for plastic/resin baits IMO. Auto clear is a good alternative for those baits, you already have the airbrush set up, probably just have to buy a new brush or tip just for the auto clear as it is a two part and can harden up pretty good in your gun. Etex or table top epoxies work well for resin/plastic baits tho. That is what i currently use on my resin baits with good results. For wood I have been using a two part epoxy set up that has had great results. First coat is devcon two ton, which is very hard, but not very impact resistant, then I apply two or three thin coats of an E-tex type product. This gets the best of both worlds for me.
Another thing, make sure you allow ample cure time, not only between coats of epoxy, but let the paint cure FULLY. The paints I use I allow 72 hrs before epoxy. This has helped durabilty of the epoxy coat by giving it a well bonded medium to attach itself too. Good Luck, hope this kinda helps hahah kinda rambled a bit