I have the Flarespace PopOuts installed as well. I am 6'1 and I am able to use them comfortably. The vertical space from where my mattress is to the pop outs is a little tight for my liking but it works great! If you have any questions on them, don't hesitate to let me know
I have them on an RB and they made a world of difference for our use. I’m 6 foot on a good day and this last trip, the wife join me and it worked out well. I sleep towards the front side of the flare, /van at its widest point. I think if you are 6’3” and above it would be too tight. Hope that helps.
Any pictures? I've seen a couple pics and they seem to look different based on if your van originally had windows vs not.