Hi John!
Welcome to the "family"! You're doing everything right, so keep up the good work. Getting used to the constraints of the harness will take time, as well as the walking on a leash part

Just keep in mind that you always want to take the ferret to a "no dogs allowed" dog park, for their own safety and NEVER let them drink from any unknown outdoor water source. Always bring fresh water for them for the trip.
Best of luck and have fun!
Jen