Johnson now has limited central midfield options, meaning Carl Winchester is needed there and cannot continue to stand in at right-back.
After losing Dennis Cirkin to a hernia injury earlier in November, Johnson admitted that he would survey the free agent market to see if he could find an option capable of helping the squad through to the January window.
He says there are 'options out there', but at this stage is unconvinced that they will be able to adapt quickly enough to significantly improve his side.
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Having integrated a number of the club's U23 group into the first-team squad behind the scenes, and having produced some impressive displays in the group stage of the Papa John's Trophy, Johnson thinks those players might represent the best option right now.
Either way, he seems likely to continue with the five-man defence that helped secure three points against Cambridge United on Saturday afternoon.
"Listen, you would consider it," Johnson said.
"You do get scenarios where players are fit, and they've been in foreign leagues where their seasons end later.
"The MLS is one example, depending on whether they're involved in the play-offs and their contracts etc, you can potentially get them for a short period of time.
"India is another example where you can potentially get a short-term deal, but the reality is that these players have got to be fit enough and they've got to be good enough.
"January is a difficult enough window as it is and certainly the free agent market at this stage of the season is a very tricky one.
"There are people out there, but we've also got an U23 squad don't forget.
"We have worked hard to integrate these players and that's why Oldham (Athletic in the PJ Trophy) is an important game.
"We want to win, but at the same time we want to protect our senior players with our league games ahead.
"You could sign someone on the free market but how long does it take them to understand the culture, the little systematic ways in which we press, the little idiosyncrasies in our possession game?
"The one thing with the young players is that they'll fight and they'll run. They're a fit group, because we'll work them harder than any squad for exactly this scenario.
"It is a big, big jump from U23 football to the top end of League One football and they'll have to be at their absolute peak to handle it."
Johnson is hopeful that Evans and Cirkin could make a return at some stage in December, with Denver Hume and Niall Huggins following in the new year.
Until then he will have to be 'tactically extremely flexible' to keep his side in the promotion race.