Re: Minn kota?
I was gonna suggest the Lehr that BLJ did, pretty cook little engines and they burn clean. I don't know anything about them except that meet a lot of your requirements I would think. The other option are the pricey Torquedos electric motors. Very nice motors but you pay for it
As Chuckles mentions you can find some good used on craigslist & pennysavers but you have to the gas issue you mentioned