Well, Cathy, I don't see how you can avoid salt in a rub intended for smoking. The chemical reactions---both within the meat, and in how the smoke reacts with it---are dependent on it.

FWIW, here is a typical dry rub as used in Texas---where "barbecue" means "brisket."

1 tbls salt
1 tbls celery salt
2 tbls black pepper
2 tbls chili powder
1/2 tbls cayenne powder
1/2 tbls wite pepper
3 tbls paprika
1/2 tbls garlic powder
1/2 tbls dried lemon peel
1 tbls dry mustard

Mix together and place in a closed container. Sprinkle generously on meat before smoking or barbecuing.

Note that as a percentage of the whole, the salt isn't that great a part. Counting the celery salt as 100% salt, the salt content is 16%.

For whatever it means, this is the same percentage, more or less, used in cajun spice mixes. For instance, here is the recipe for Emeril's Essence:

2 1/2 tbls paprika
2 tbls salt
2 tbls garlic powder
1 tbls black pepper
1 tbls onion powder
1 tbls cayenne pepper
1 tbls dried oregano
1 tbls dried thyme

Essence actually is a simplified mixture. Here is a cajun spice mix I learned down in the swamps, while duck hunting with some Cajun fellas:

1/4 cup salt
2 tbls paprika
1 tbls balck pepper
1 tbls garlic powder
1 tsp chili powder
1/4 tsp ground mustard
2 tbls cayenne pepper
1 1/2 tbls onion powder
1 tbls white pepper
2 tsp basil
1/4 tsp thyme
1/8 tsp ground cloves.

I also learned how to make genuine gumbo from those boys. But that's a different topic.

That really is the question, when it comes to smoking. Or barbecuing at all.

Folks have actually come to blows over this issue.

However, on the assumption that you do sauce, the question is, "when?" And that one's simpler to answer.

If you sauce the meat ahead of time, and/or continue brushing it with sauce as it smokes, you're gonna be disappointed. Under low & slow conditions (actually, even more so over high, direct heat), the sauce first caremelizes (which is good) and then carbonizes, forming a burnt crust on the meat.

Most people, therefore, sauce after the fact.

However, if you want a baked-in sauce flavor, there's nothing wrong with brushing the meat with your sauce during the last half hour of cooking. This will give you that caremalized coating that tastes so good, but you won't need a jackhammer to break through it.

So, in a fit of pernicious boredom, I spent a goodly part of the day looking at what must be several hundred rub recipes.

With one exception, all dry rub recipes included salt as an important measured ingredient. The exception includes "salt to taste" in the ingredients list.

Interestingly, many of the wet rubs leave the salt out. I suspect this is because wet rubs stick better, to begin with. And, if there were a pelicle formed, their flavors wouldn't penetrate into the meat.

That is a guess on my part, and I would love to hear from anyone with a more definitive explanation.

I smoke on my gas grill. I soak wood chips in water. For longer cooking times, I use two pans for the chips. In one pan, I place 2 cups of soaked chips. Same in the other pan, but I add a cup of water to act as a "time delay." I put these over the back burner, and leave the other 2 burners off.

For brisket, I use a dry rub, and tent with foil, and smoke for 3 hours. My grill stays at about 250-275 degrees.

Then I wrap the brisket in foil and finish in the oven for 1 1/2 hours.
It comes out really tender, and the leftovers are great for sandwiches.

I also smoke salmon with this method, but I brine it first.