Peter if you choose to clearcoat the body work and you use 2K clear then airbrush very thin "tack" coats first 2 or 3 coats before you try to apply a thicker "flow" coat that looks really glossy.
2K clear is very chemically reactive and gets hot when it cures - This can cause the decals to melt okay - so for the first 2 or 3 coats of 2K clear just "mist" it on with an airbrush so that the decals get sealed under the misted clear and give it a day to cure before you apply the flow or wet coat of 2K clear.
You have done an excellent job so far I would hate to see the decals damaged by a heavy coat of 2K clear.
Cheers Peter
John