Keith,
About you being 6'3". I'm 6'1" and my standy bed is 74". a bit short for us but it is 60" plus wide without any side walls hampering your sprawl. I get by pretty good but I sleep wrapped around the wife on a diagonal. I've decided that the interior minimum size for a teardrop would be 58" x 78 or 80". Decide how much room you need for the lower part of the galley and wall thicknesses and that will add up to your length. I could probably get by with a 5x8 but would be much more comfortable in a 5x 9. Just remember that the "cute" factor may be reduced by the extra size.
Jim