If your model is smallish and doesn't produce much vibration, the all thread will work. The ally tubing needs to have a good wall so that it can be tapped

But beware if it's engine powered.....all-thread is typically not made from better steel and will fatigue relatively fast. I made the mistake once 25 years ago give or take. Never again. And aircraft grade ally tube should be used not the cheap tubing from the LHS

The better solution by far is Aussiesteve's recommendation or make your own with carbon tubing and higher quality steel bolts with the heads cut