I've thought about how hard it must be to be a lefty fountain pen user. What is one to do? Learn to write without resting your hand on the page?

Actually, paper orientation was a big help too. Used to tilt the sheet so you write almost bottom-to-top, that way you at least don't smuge the writing right away, and hopefully the ink dries quick enough for the next line

If you read the linked post, he covers this