Attaching placards in the rain?

Sounds like you have it figured out.

 

Things must have changed since I've had hazmat.
Used to go through scales All the time with placards ductaped including Ca. Scales.
And yes I mean along all four sides of the placard.

Since when can you use only use clear tape?

 

What about?
Using ductape ?

 

They claim it us modifying placard and subject up to $1500 per placard fine.

 

Packing tape works best. Alcohol to clean, no windex or ammonia cleaners. Although the suggestion of spray contact (aerosol fabric/upholstering glue) cement would be awesome
If I get hazardous and there are no placard holders I make it the companies responsibility to apply placards,, then I take a pic of all 4 corners. Has not happened in a year as nearly all our trailers sport 16 placard holders.

 

I've used spray contact glue stuff in negative zero temps on FRP tankers. Worked great for sticking them on. Used a body decal remover to take them off. PITA.

 

Any water based adhesive should do the trick, but like has been mentioned, they aren't going to come off easily.

 

Don't worry about it.

If you can't attach the placards just go with it. Stick them on when you can.
Or, you sit where you are at until you can.