Reusable placards

[dhirocz]

I tend to pull around alot of 20' ISO tanks locally that sit in our Depot yard for awhile...as a result, the placards tend to get really shitty and need to be replaced as they are no longer DOT legal.
Problem is, my terminal can't keep vinyl adhesive placards on the shelf it seems. Driver's seem to hog them when they put them out.
I certainly can't be driving around with tanks that have messed up placards. Half of the tanks are so dirty on the outside I need to clean off a spot with brake cleaner just to make vinyl placards stick.
Since I usually pull around tanks that are placarded the same, I'm wondering if anyone has used flip placards and mounted them to a magnetic base to make a reusable metal placard. I get paid $90 to replacard a tank, but it seems the only surefire solution is to buy my own placards...takes time and isn't cheap. Normally I'd ask the shipper since it's their responsibility...but they are in China and by the time the tanks get here, the placards are all tattered.

If I put magnetic placards on the frame of the ISO tank, do I still have to remove the tattered ones from the tank to remain DOT legal?

Just looking to run more efficiently. I have a high turnover with these, and time is money. If I can snap placards on the frame all around, collect $90, remain legal for 40 miles in transit, return the tank and remove my placards without having to mess with the ones on the tank, that's a win.