Maybe this will help from a 6'6" guy.
Rumor has it Gossamer Gear is switching the foam they use for their pads which will allow them to cut it in nearly any size. They are also going to offer tall packs. Having used their foam in winter, it is "good enough" for even fairly cold temperatures and you can double-up on it for more warmth. The down mats, inflatables, etc., are all heavier, more expensive, and are not the right size. Consider GG's closed foam as an option.
Talk with Grant to get the specifics. I'm not saying it's gospel and I don't have an exact date, but these things were mentioned to me personally by GG.