Why don't you just retrofit a conventional touring bike using the components you like? Pictured below is my Bruce Gordon with a (now unavailable) BionX hub motor. You could do the same with a Surly LHT or Trek (or Cannondale if you prefer aluminum) using a Bafang mid-drive motor. The suggested Riese and Muller looks like a beast at 69 pounds. Mine pictured is about 47 pounds with one battery, add 9 pounds for a second.
I could put the front racks back on but am currently using that location for water bottles. As you can see the main triangle is dominated by the battery. Under down tube location is where I carry a pump. You may need to carry some water inside the bags as suggested on the other thread.
Keep in mind that any touring ebike may require two batteries and two chargers. Carrying luggage you're likely going to need to stop every 50 miles (or sooner) for an overnight re-charge. After 50 years I've retired from long distance camping/touring. Just too many challenges with re-charging on the road and carrying extra batteries/chargers.
