Re:
Apply the decals on the basecoat, then then apply the clearcoat, first of all apply a very light dust coat over the decals, to seal them in, the only time they will shrivel up because
1: an excessive amount of thinners in the 2k clear coat will eat into the decals, hence the reason for applying a very light coat (less thinner content) seals the decals in. A word of warning, do not be tempted to reduce the amount of thinner in the clear coat, as this will create other issues with poor application (orange peel) remember the ambient tempreture is critical as well, this includes the tempreture of the frame, always refer to the product infomation provided with the clear coat. the correct application tempreture allows the thinner to evaporate quickly, thinner is only a means of transporting the paint from the gun to the frame.
2: cheap decals will always be more likley to react to any kind of solvent thinner (avoid them, its not worth it)
Please pm me if you need anymore advice, I dont mind helping felow Retrobikers out.
Stuart