They announced the signings of Michael Palm Toft, Nike Lunna and Emil Grondal, as well as the returns of double-winners Ulrich Ostergaard and Simon Lambert, before Christmas.
That left them with 13.76 points available to complete their septet, but the remaining two slots have since remained blank.
Now, with the new campaign barely a month away, Johnson confirmed the final pieces of the jigsaw have fallen into place and the full team has been sent to the British Speedway Promoters’ Association (BSPA) for approval.
He said: “We’ve declared our team line-up to the BSPA and we’re awaiting confirmation that it has been received.
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“We’re very happy with the two final signings to complete our side and we’re hopeful they will be approved very soon.
“We realise it has been a difficult winter, but we appreciate the patience shown by our supporters and we fully intend to repay them by being successful on the track.”
Panthers had struck a deal with seven-time British champion Scott Nicholls, but he was then blocked from racing in the SGB Championship by new BSPA guidelines.
That left both parties in limbo, but speculation in the sport now suggests the rule blocking Nicholls from joining the club is in the process of being overturned.
It is thought he will occupy one of the two remaining spaces in the Panthers side with a reserve rider completing the order.
Panthers are not the only team still to finalise their riding plans. Fellow SGB Championship sides Newcastle and Scunthorpe also still have empty slots.
The 2018 campaign begins when Panthers stage the star-studded Ben Fund Bonanza individual meeting at the East of England Arena on Sunday, March 18.
The club’s first competitive meeting follows a week later on Sunday, March 25 when they entertain newcomers Lakeside Hammers in the group stage of the League Cup.
Panthers still have season tickets for 2018 available. They are priced at £240 for adults and £190 for concessions and are available by visiting http://www.peterboroughpanthers.co/ticketoffice and completing an application form.
The club’s annual Press & Practice event is being held at Alwalton on Saturday, March 17. Exact timings are still to be confirmed.