And the Lockheed P2V-7 Neptune to say nothing of the Boeing KC-97L and many others.
Relit at 40,000 feet?
Don't think so.
Now, I did fly Stratocruisers (close cousin of the KC-97) for a brief while and they had a hard time getting above FL210, normally.
In actual fact, the J47 jet engines on later B-36's could be (mostly) routinely restarted at 50,000 feet, to enable high speed bombing runs.
This was on the 'Featherweight' models, which had much equipment removed to attain these altitudes.
A quite unique airplane, the 'ole B-36, and it kept the Russkies at bay for quite some time.