I wasn't a fan of the Lil' Pals harness simply because it still put pressure on the neck and I know Gizmo wasn't comfy walking in it. Did you think about maybe using a harness vest, or step in harness??
Here are some links for them:
Harnesses, Puppia, Doggie Design Step In Dog Harness, No Choke Dog Harness, Harnesses for Small Dogs , Puppy, Pet, Or Cat
Once I got Gizmo a step-in harness, walking became alot easier. Another trick that worked for him, is when we were training him, we walked him with my mom's dog, or took him to a dog park to have him observe and mimic.
Good luck!