Who has done this on dirt/gravel roads on private property? How effective was it? Any tips on the application? Any tips on what NOT to do?

I have done it for years. I take the bottom of the barrel, spread it on the road and try to stay off it for a few hours while it soaks in. You want it to be warm out, not winter time.
After awhile you will get a paved road when it polymerizes. I have had people think that my drive was paved. Works great.

OK then. Test strip to be poured this afternoon. Thanks

I have done this as well.

If you do a search for you will see several others that have done this as well.

One caveat.
Make certain that no animals that might lick the grease are able to.
They also ingest gravel and with enough it will kill them. Dogs especially like the tasty road treat. Slow and painful death so be careful.