Hi Ken,
My grapes are from my own small vineyard, from my front yard in the East Bay.
I make about 20 to 25 gallons of Cab on average, some times more depending on a number of factors I’m still trying to understand.
My worst year was in 2015 and my best in 2016 when I made 35 gallons from only 44 vines.
Regarding barrels, I don’t have any, I used oak sticks in the beginning, but for the last three years I have been using Hungarian Oak cubes.
Barrels in my opinion are difficult to deal with, tricky to clean and sanitize, may leak as you experienced and of course expensive for a useful life of only three years.
You mentioned about your garage temperature getting in the high eighties, that is definitely too high.
Have you consider building a wine cellar, or at least some temperature controlled cabinets in your garage?
You also mentioned about using a testing lab in Oregon, but there are also local labs such as: ETS Labs in Sonoma, Busters Labs in Livermore and some others you can find just by googling.
Cheers!
John