Nice groove. I think what you have would work well as an extended solo outro. The only thing I might change here would be to add a little extra "color" somewhere in the middle to spice it up. For example, the chord progression you use repeats 10 times, maybe on the 5th and 6th time add a synth pad with chords to brighten up the texture a little bit. Then remove it and return to normal on the 7th time. Or something to this effect, so the accompaniment isn't the same throughout. Just a thought...
I think this would work. Maybe have your overall structure be Verse-Chorus-Verse-Chorus-Outro(using the solo you posted here). You could have the verse at approximately the same "energy level" as this solo, then make it a little heavier for the chorus (maybe add some distortion to your guitars, or some heavier drums... not too heavy though, it definitely feels like it should all be laid back to me). Then have a second verse-chorus similar to the first. The beginning of the solo you posted could be a "drop" before the solo guitar finishes out the song. It might be a little tight, but I think this would end up being around 4 minutes.