Decal application question

[foulrift]

I am in the process of applying the finish colors to some reefers that I am building. If I remember correctly,decals should be applied to a glossy surface but these colors are on the dull side. My question is this-should I spray the car sides with a gloss coat before applying the decals? If so can the car be weathered over the gloss surface or should it be weathered first? The reason I ask is I want to be able to apply weathering over the decals.
Any suggestions will be appreciated.
Bob