Despite 9,000 fans not renewing season tickets for the club's Irn-Bru Third Division campaign, the Light Blues have sold more than 38,0000 season passes, higher than previous years when they were competing in the SPL.
And Green reckons the current 51,082 capacity at Ibrox may not be enough to satisfy demand from fans.
He said: "It is further down the line. I have said, and it is a discussion I have had with Ally McCoist, and he knows this club significantly better than I do.
"He said 'look Charles, if you can achieve your dream and deliver that of us consistently (being) in the Champions League and getting to the last 16, then this stadium is not big enough'.
"Even though I wasn't at Rangers, I saw the turnout when they all went to Manchester so I do know what is behind this club.
"One of the reasons for the IPO (Initial Public Offering) and bringing institutional investors to Ibrox is that if, and when, we get to that position, as I am confident we will, it is a discussion this board will happily have.
"With the way the ground is configured, there is great opportunity to fill in the two corners, put another deck above the Argyle (Suite) and that would substantially increase the stadium capacity.
"We wouldn't be frightened of doing that once we know we have got the demand, and the top league in Europe would deliver that."
Green met with fans this week to lay out his blueprint for Rangers' return to the top level.
And he has revealed former Gers administrators Duff and Phelps have approached him about investing in three other clubs..
Green told Rangers TV: "It is interesting that Duff and Phelps contacted me. They've obviously been contacted by investors, shareholders or clubs, and clearly it would be improper to name them.
"It is flattering in some ways that people now associate Charles Green with rescuing football clubs.
"But the message on [Wednesday] night wasn't about my position it was about the state of football.
"It is not just Scottish clubs that are having difficulty.
"This is now appearing in the UK, in Championship clubs. These are not lowly bottom-division clubs.
"I think there is a downward force in football and we have actually now turned against that movement and gone forward.
"I said to fans that I came here, unashamedly, to make some money and disappear but, during the process that has changed."