What looks neat and meets Code: mount a receptacle within a junction box in the soft lid.
CADDY and B-Line make supports for it. (512)
Then just plug the SOJ into the receptacle.
SO/ SOJ cannot go above the lid: not rated for the heat up there.
The run from the receptacle junction box to the branch circuit would normally be MC.
A seismic wire to sustain the j-box would also be in order.
Otherwise, go all of the way with MC/ Greenfield. It looks nasty going through the lid. But it costs less.
You choose.
