Amid an on-going battle for control of the Scottish League One leaders, Craig Mather resigned his post as chief executive by "mutual consent" last week with non-executive board member Bryan Smart also standing down.
The latest departures followed those of non-executive director Ian Hart and chairman Walter Smith to leave just two board members of Rangers International in situ - finance director Brian Stockbridge and non-executive director James Easdale.
Shackleton, from Daniel Stewart, the club's Nomads (nominated advisors), admits having just two directors is "not suitable" and is busy trying to find a resolution to the Govan club's boardroom problems.
"I can't go into detail but I have been speaking with shareholders," Shackleton told Press Association Sport.
"We are actively trying to sort the situation out, we are doing everything we can to get it sorted. It needs stability.
"I have been talking to everybody, trying to map out a path through this minefield.
"Once we have done that I think we can make a decision.
"There needs to be more directors at the club. Two directors are not suitable for the long term.
"But I've not been sitting on my hands. It is a very complicated situation and we are doing what we can to sort it out.
"There is a process to go through and I'm trying to come up with ideas.
"We are very keen to get it resolved as soon as possible and I think I am making progress."
Last Monday, the Court of Session in Edinburgh forced Rangers to postpone its annual general meeting, initially scheduled for October 24, because they had refused to include on their agenda a request by shareholders for the election of four new board members, including former chairman Malcolm Murray and former director Paul Murray, as well as their allies Alex Wilson and Scott Murdoch.
Lord Tyre ruled that there was "no valid legal reason" for the Rangers directors not to present the motion to the club's shareholders.
A new date for the AGM has yet to be decided.
In the club's annual accounts, it was revealed that Rangers made an operating loss of £14million in the 13 months to June.