Rob and I crossed the Gulf of St Vincent in South Australia - http://www.hobiecat.com.au/bb/viewtopic.php?f=22&t=589
31 NM in 7.5 hours.
This doesn't compare to your plans but we did a comprehensive
risk management and passage plan which may give you some "ahas".
Have a look at -http://www.hobiecat.com.au/bb/viewtopic.php?f=22&t=601
We were able to maintain radio contact with 5W radios, due to the distance.
We went West to East due to the winds and didn't paddle at all.
Rob has Haka seats and tramps on the kayak we used.
This with a tiller extension allows holding down the windward ama and
helming from there. Probably the biggest advantage of this setup was
the ability to move around the craft and sit in a different body position.
It is even possible to lay on the Haka in calmer waters.
We didn't have the overnight considerations that you will have but there
are quite a few that have camped out.
I also have an engine mount and a 4 HP outboard which works well.
Because of the winds, we didn't bother to take in on the crossing.
Anyway, keep the forum going, we will all be interested in your setup
Cheers, Brian in South Australia
Tandem Island -