You should do fine with the deep divers once the coho show up.

BD (before downriggers) I did a lot of mooching/motor mooching and was reasonably successful. For motor mooching use your standard mooching setup with a 6 foot leader and banana sinker. Let your gear out to the desired depth with a controlled free or by counting pulls. After your line is down pop the engine in gear and let your bait work its way bay up to the surface. Once there, put it back in neutral and let your line drift back down. Its not as precise as downrigger fishing, but allows you to work different depths fairly easily until you identify where the fish are.
JMS