Despite the fact this is legalized highway robbery, anyone by now should know that it exists and take the precautions. It’s also a fact that most cash has drug traces on it and will automatically set off the dog.
Seal the money in a ziploc back inside another, both sprayed with Febreze, inside a hermetic sealed lockbox, inside a locked suitcase filled with clothes, sprayed again with Febreze, and locked in the trunk. Wash your hands after handling the money.
A little effort will go a long way in avoiding having it happen in the first place.
And if they searched your car for some reason anyway, and found your money quadruple-sealed and double-sprayed, then they would really think you had something to hide.
Civil forfeiture laws without trial are an obscene violation of the Constitution, and a swift road to police corruption.
And as a practical matter, the War on Drugs is a failure and is the cause of the corruption.
Use a cashiers check, as you say most large bills have coke traces. If you want to deal in large amounts of cash have the person you are dealing with come to you.