Allen believes it is a gamble worth taking in allowing Campbell, who has shone in the Ryman League - and against Newcastle in the Cup, the chance to make an impression in the professional game.
"DJ is a centre forward who has been prolific at non-league level, and I am going to take a gamble that he can deliver at this level," said Allen, whose side lost out to Sheffield Wednesday in the play-off semi finals last season
"He has energy, enthusiasm and self-belief and has got himself going after a tricky couple of years."