Neat appearance, friendly demeanor would go a long way.
Look more like a "backpacker" than a homeless vagrant.

Maybe have a backup story of "walking to find a cure for sick honeybees" or something. And be sure to have a spotless police record because you can be sure that you'll be checked for wants/warrants.

The knife in your possession *could* be an issue.


(On previously mentioned motorcycle trip I actually ate lunch with a motorcycle cop. I was glad for the company. )