I'm not sure the hoop house is really necessary unless you are trying to protect the plants from insect pests. In fact, the hoop house may be containing the pests you are trying to manage. You may have more than one pest as there are a number that can affect cane berries.

Cultural controls such as removing any fallen leaves and fruit is a good start to preventing overwintering of pests. You need to watch in early spring for the adult emergence of moths and flies as I found several types of pests that could be causing you problems.
https://pnwhandbooks.org/insect/small-fruit/blackberry-raspberry/blackberry-raspberry-looper
https://pnwhandbooks.org/insect/small-fruit/blackberry-raspberry/blackberry-raspberry-leafroller
https://pnwhandbooks.org/insect/small-fruit/blackberry-raspberry/blackberry-raspberry-raspberry-beet...

If you do need to use chemical controls, spinosad is common to all the pests above. The links provided list chemicals that are approved for home use.  Please be sure to read the directions prior to any application and then follow the directions and safety precautions.

You certainly don't need it for any cold protection as the plants are well-suited to our climate.

Pruning of raspberries can be tricky as there are two types: primocane which bear heavily on the current year's growth and floricane which bear on the previous year's growth. I have "Willamette" which is floricane and I pruned out all the old canes in late summer, and I tied up the new canes to the support. I'm about ready to cut off the canes to about six feet (some are >10 feet long)

Your blackberry is floricane so the new growth is typically prostrate on the ground until the current year's harvest is done and the old canes removed.

OSU has a couple of publications you may find helpful
https://catalog.extension.oregonstate.edu/ec1306/html
https://catalog.extension.oregonstate.edu/ec1303/html