I need to equip a sailing boat for battery charging for a single long haul
trip of about 35 days.
This will be a delivery trip for a boat that will not need any such
capability once it arrives at it's destination. Much of the power
requirement will be to drive an autopilot and attendant instruments and nav
electronics.

I've looked at Solar but I don't think it will be economical to buy the
solar panels that would be required.
I could run the 30 horse diesel for a couple of hours per day but I know
that diesels don't like light loads for extended periods.

I've discounted wind systems because of cost and also some concern about the
ability to reliably generate enough juice as well as noise and safety
issues.

I'm also thinking about using a Honda Portable generator with it's output
connected to the existing shore power system battery charger. Upon arrival
I could easily sell the generator for something like 75% of it's cost or
just keep it. The main disadvantage I can see to this approach is that I'd
need to carry petrol (gasoline) to power it and that consitutes a
significant bit of a safety issue.

Anyone care to comment on the Honda Generator idea?
Any other good ideas that I haven't considered or flaws in my logic?