I have a 30 foot long 1997 Bounder with the 225 HP rated V8 Ford. I bought it new when I heard the V10 would be the only FOrd engine in the 1998 models, and I did not want the smaller engine. Sadly they improved on the horsepower and weight ratings because they also upgraded brakes and went from 3000 pound 16" rim to a 3,500 pound 19.5" rim.
Anyway I have been happy with my gas engine, and really only put about 50,000 miles on it in the 18 years I have owned it. So if you will average around 5,000 miles a year, then fuel costs will not be as significant as insurance and payments.
It is nice that I can do the oil change in my driveway for about $50 with only 6 quarts of oil, and a bargain oil filter when Fram is on sale for only $8 or so. Compared to a diesel with 28 quarts of oil (also need to get rid of those too) and more expensive oil filters.
I found that I have plenty of power. My buddy with a 40' Country Coach (1998) that is heavier takes longer to climb into the mountains, probaly due to it's weight or 2,000 RPM redline, so the power is a LOT but RPM is really slow compared to a gas engine. The 6.8L V10 is happy to run 4,000 RPM all day long due to it's cylinders only being about 0.68 liters. A 10 liter inline 6 will have nearly 2 liters per cylinder, so the stroke is much longer and bore is huge compared to the V10. This is why RPM is so limited in a diesel, except for the V8's used by Ford and GM.
Another buddy has a 1987 class C with a 460" V8 that has been rebuilt for power, increased compression, ect. It will outrun his neighbor's CAT powered 40' DP on the hills too. He just sets the cruise control at 65 and goes up and down the hills without any problems. The DP is down to 45 on most grades.
Good luck,
Fred.