phughes

There are plenty of bike specific posts there. The people on that forum, as a whole, are better equipped to answer your question. There all types of bike tourers there, some that use traditional touring bikes, converted mountain bikes, gravel bikes, and even lightweight bikes.

As for aero, if you are using panniers, a more aero bike won't help, however, if you post this in the touring section, you will get people answering who can show you how to mount bags that are more aero, though that will include more than simply buying a bike, you will need new bags, and they will not hold as much, but it will get you more aero, as you seem to want. There are many people touring like that. You can use frame bags, and bags mounted behind the seat. You will give up carrying capacity though. It all depends on what id important to you. Going light may be freeing.