Don't over think it. I am 5' 7". I have a 17 year son who is 6'3" and a 18 year old son who is 6' 4". It's feaseable. They can still have grow up to 21 years old!
My boys are young (5 & 6), but my 6 year old is only a foot shorter than me right now. This momma is also going to be in the same boat as you!
Van dinosaur what you put sounds like what I thought as well!