There shouldnt be any gas smell unless your motor or tank/fuel line leaks. Fix it. As far as exhaust chasing away deer, we use ATV’s all the time to get within 75 to 100 yards of the stands with no problem with noise or fumes etc effecting the deer coming by. Stinky diesel farm equipment are in the fields and deer walk past them. Sounds like a Geenoe or other square sterned light boat is what will work nice in your situation. The kids ride their 2 cycle dirt bikes around the farm that has plewnty of deer, on the trails in the woods and they are not scared away much and always come back. Good luck with the boat find, craigs list is good. I bought a Coleman square sterned, wide canoe a few years ago for $80. Great deal.