Is it disrespectful to run a turkey trot (and win) without being officially entered?

Yes, it is disrespectful.

My recommendation is to just do what I'd do--what I want and choose to not give a damn. But I would add that banditing and not paying the entry fee to join an organized race is not entirely appropriate. If you do pay the entry fee, then do whatever you please.

Bandits are rude, selfish people. I despise those me-first-you-last types.

I once had the misfortune of being told I was a bandit. It occurred during an out-and-back 10k. I was on the back to my car along the path used by the race. I was out for a 16 mile long run. I had no idea there was race set to use the same path. I found myself merging into the race because there was no other way back ... except into traffic, or off a beach side bluff. I was running a slower pace than the runners I merged with. Two guys running together ran by me, one said, "course cutter", the other said "bandit." I ignored them, and found it amusing how rude some runners can be. If they knew who I was, and LRC existed in the late 1980s, I am sure they would have started a thread, "Got one. Cheater cuts course and bandits. Who do I report them to?"

Pay the entrance fee you cheapskate.

If they've paid for road closures, then you aren't free to just run on the road.

Maybe you should enter earlier next time.

Drive to the next town and do their turkey trot. Every freaking town has one. I can think of like five right now off the top of my head, without researching more- that I could reasonably drive to and go run on Thanksgiving. I'm sure you can too. Or run a race another day. They have races every weekend out in the world, you know.

Banditing is always a real d move. Real runners don't like that.

Contact the race organizers

how do you win a race you haven’t entered?
you can run in front of everyone if it makes you feel special but you still won’t win.

provided the leaders know you aren’t part of the actual race then the harm done is minimal.

Disrespectful.

Legally speaking, it's theft of services because they're keeping the course safe for you and you're simply a bandit- that sucks. If too many people were that rude we wouldn't have races at all.

Pay the money and run or just run the distance on your own somewhere else.

No race limits entries to 120. None. You are trying to justify cheating by presenting false information.

I hope you consulted your lawyers on this.

The municipality issues permits to the race, and the municipality can restrict access to its roadways during the race enforceable by civil and/or criminal penalties. Hey man, you do you, though.