Hi Jackson 74,
Another V10 owner here. No problems with ethanol gas....just poorer mileage. These new engines seem to have figured out how to deal with the ethanol issues. I do put some additive in the fuel if we are going to let it set for more than 30 days. That seems to do the trick. Runs great (even the generator).
For our 26 foot Class B+ the V10 has plenty of power so we haven't made any modifications. Rather spend that money traveling. Get around 9mpg average with a light foot and no toad.
I was also perplexed with the 5/20 weight oil, but it does not seem to use excessive oil and I think that it helps with the mpg. The V10 is a bit thirsty, but very reliable.
The more I RV, the larger my bucket list becomes. Enjoy your travels.