I've got over 10,000 miles on my Corbin seat now and its broken in perfect and it makes my rides every few weeks to Los Angeles and back to Northern California on my Zero so easy. Mine I can slide forward at stop lights or slow speed riding around town, but when getting on the highway I slide back all the way, put my feet on the passenger pegs and Charger actually slides back too and lays down.
Here's a pic I got sent to me a couple days ago (although the pic is 3 months old) with me sitting in the middle of my available range. Can slide back more or go forward. The Corbin is great! But it's a little hard to start from what you expect.
But its supposed to be that way. It's like a properly sized helmet will feel like it's too tight and uncomfortable for the first few weeks, until eventually it fits the shape of your head perfect. Just so you don't plan 1000 mile trip the first day you get it. Lots of small trips the first couple months will prepare it for that Iron Butt attempt.
The last pic is me picking up a friend from the airport a month ago. So I slide forward, and it leaves room for a passenger. But when riding alone it offers a huge range of mobility which is how I ride most of the time. If you are well under 6 feet you can get Rox risers for your handlebars so you can reach them easier while sitting all the way back. Once you have these choices you'll really appreciate it more if you ever have to ride a stock seat again. Sort of like those of us who didn't mind the Fast Ace suspension at all, until we rode a 2015 and 2016 for a while with the Showa suspension and then we went back to a 2014 or earlier for a short ride and were like "Woah! Where did all the bumps come from in that road??"