Sandpaper is very effective at getting off some of the residual spots of carbon buildup and spot-cleaning rust. I’ve also heard that using an electric sander with 60ish grit can be very effective at smoothing down a rough finish. I’m going to try it myself with a customer’s pan here soon, but definitely wear an N95 if you’re going to do that!

Honestly I think you’re going to get smoke with virtually any seasoning oils or fats. Even if you don’t hit the bona fide “smoke point” you’ll still get a bit of smoke naturally, be it from natural impurities in the oil, residual seasoning or flash rust on the pan, grime in the oven, etc.

Best thing you can do is just get really good at airflow maintenance.

I use homemade ghee, a very thin layer that I towel basically dry, oven for 1hr or so at 485F. I was doing it at 525F before but I find that the lower temp also works great.

The current photo was only with one cooked layer of seasoning, plus a new one that I had just toweled on which is what the photo is. I usually just go for two coats + top layer but plenty of people swear by more. Just never really seemed worth all the extra effort to me when cooking will give you the seasoning all the same.

Suggested reading: https://sherylcanter.com/wordpress/2010/01/a-science-based-technique-for-seasoning-cast-iron/