Ok, after all of that, here's what I think: your Provari is about as good as a mod gets in the low power regime. I seriously doubt it has anything to do with it. Also, the various Nautilus tanks are very well thought of in the MTL regime. I have seen a bunch of people quit smoking using them. Assuming you are buying authentic Aspire Nauti coils, the only thing I can assume is you are using a gunky juice that's killing your coils. Sweet and/or dark colored juices are known for this. You may wish to upgrade your Nauti to the latest model, the Nautilus X, see if that helps any. Another solid choice would be the House of Hybrid Kabuki tank, allegedly the best drop-in coil MTL tank available. It uses Nauti BVC coils, too. They're quite pricey, so I'd suggest trying a clone first, to see if you like it, before blowing the bucks on a real one. I dunno about clones, but the real ones are also available P3 threaded specifically to fit a Provari with a stronger connection, assuming yours meets this criterion.
If that doesn't work, then it's time to learn how to build your own coils and wick them. If nothing else, it's tons cheaper. There are excellent MTL RTAs out there, and you can, if you wish, pull a fresh wick with every tankfull, which should keep your flavor bright. If you move into built coils, you'll quickly see you don't have to replace the coil itself anywhere near as often as the wick. Just take out the old wick, burn the coil clean, pull a new cotton (actually, I recommend rayon), refill the tank and vape on.
Just a thought.