this is the way to go
http://www.pet-shop.net/html/repleash.html
dont use a leash if he freaks just the harness.
Dragon's are very smart and can be trained mch like a dog.
If he knows freaking out will get him to get the harness off it will always do it.
Leave the harness on and comfort or distract him if he starts to freak out.
He will eventually become tired of throwing a tantrum and embrace the harness.
A treat after you put his harness on is a good idea as well. He will associate being rewarded
while wearing it. Be patient, 3-4 days max hes trained I bet.
Then just die the harness Safety Orange or sew on the key finder thingy.