Morin pauses for a moment to examine the door more closely; he is especially interested in finding any gaps around the edges. In any event he will eventually attempt to listen at the door for any sounds beyond. If he hears nothing, he will attempt to force the door open.
Morin waits at the corner for the rest of the scouting party. When they arrive, he stoops to speak to them in a hushed voiced. "I am suspicious of this passageway; we have turned several times, and should now be back upon the entrance. Perhaps there is a secret portal; perhaps there lies a tra...
Note that Morin already carries a lantern. If Boggs carries a torch, perhaps your first proposed marching order works best, as we'll have light at the fore and at the rear. Morin is fine with that — proceed!
BTW: Brother Walfried, Morin likes the cut of your jib!