Attaching placards in the rain?

Need some ideas adhering placards to a trailer with no placard holders.
I'm planning ahead,dont know what I'm hauling...guessing it's paint.
Any adhesives work?
Last time I had multiple placards to apply,used all my bath towels to dry trailer the best I could..still lost placards and had to replace every time I stopped...

 

Name is schleprock...it's always raining in my world...

 

That makes sense but has to be clear tape..

 

I guess I could double side it and use it on back side of placard,then use clear on the outside.

 

Usually takes a while for the Velcro to adhere,little place I'm loading,the dock is directly off the road,and the road is filled with waiting trucks..and my clock will be running..I'm thinking using the duct tape on the back side makes the most sense.