This can work in the spooning position (I really can't imagine any other position that would be comfortable) and only if you're both dead tired and just pass out right after sex or doze for a bit and then kind of wake up and feeling it get hard again so you can move on to round two. I've had this happen on occasion but it's always been more of a natural and organic thing - not something you're trying to really maintain on purpose - and only for shorter bursts of time (like a doze or nap).
To be honest - I don't like excessive cuddling that goes on all night. I really do like my own space for actual sleeping and chances are high that after sex, I'm probably going to get up to go to the bathroom or get a glass of water or something before settling in for the night anyway. Unless as I said before - I'm dead tired or kind of drunk. I like the concept and am definitely in favour of leaving it in until it gets soft or you're done with the cuddling session but not all night - it's kind of constricting.
Guys that have done the all-night cuddling thing with me have been a turn off - mainly because I can't get a proper night's sleep and I'm the type that doesn't need nonstop touching to feel connected or a sense of intimacy.
I'll take the cash. Easy. I have no desire for immortality.