The OP posted:
when the elevator cable snapped just moments before landing
That is a very different situation from a landing planned with time to allow for an alternate method of pitch control.
If you cant fly it with a trim wheel, get the attitude you desire by having the pax move up and down the cabin.
If the aircraft nose is too high, fill the front seats/ aisle, laps. If the nose is too low get every one in the rear... FO too if it helps!
This would be a really poor idea, re configuring an aircraft in a uncontrolled manner, with undisciplined occupants, who would now no longer be secured in the aircraft is asking for trouble! Too many people move too far, and you're out of C of G limits, out of control, and not going to regain control - and you asked them to move! Not when I'm flying!
Non event - just fly it with the trim wheel.
If you're having to consider flying with the trim wheel, for loss of other control, it's an event! The trim wheel, with practice and time to perfect technique, can be used to set up a landing, but certainly not at the last moments on the approach. The Twin Otter is a more pitch sensitive than some other types. Changes in flap position, or power, can affect pitch of a Twin Otter more dramatically and suddenly than other types, flying by pitch trim alone is not a last minute alternative.
The design requirement associated with this characteristic:
(e) By using normal flight and power controls, except as otherwise noted in paragraphs (e)(1) and (e)(2) of this section, it must be possible to establish a zero rate of descent at an attitude suitable for a controlled landing without exceeding the operational and structural limitations of the airplane, as follows:
(1) For single-engine and multiengine airplanes, without the use of the primary longitudinal control system.
(2) For multiengine airplanes--
(i) Without the use of the primary directional control; and
(ii) If a single failure of any one connecting or transmitting link would affect both the longitudinal and directional primary control system, without the primary longitudinal and directional control system.
Nothing there says "suddenly" or "at the last moment". It also must be practiced.