Thanks.

The trees that I am looking at are Negronne, which I am told do not get huge.

I should add that the 3 foot trees that I found are the Oregon Prolific and Desert King and Brown Turkey, all of which do get big, I believe.

The Negronne, which gets about 10 feet, is available in 2 foot trees. So, I may just have to start small, very small.

Modern places often have no room, vendors routinely give tiny size representations. With woody plants there is a tradition of giving typical 10 year heights. If somebody is figuring 10 ft. in 10 years for the 'Negronne' then that means it might be approaching 20 ft. in 20 years. However, in food gardens woody components are often heavily pruned. This can have a satisfactory outcome as long those doing the pruning know what they are doing.

Isn't the sun pretty high by the time the Apaches leaf out and resume growth, or is that caneberry variety mostly evergreen here?

My apaches are already leafing out...

...as are most of my caneberry varieties, but they will not be a sun block anytime soon. Most caneberries can be pruned quite low and still provide a crop, height of canes can be increased yearly as nearby fig matures.

I really don't expect the brambles to be any problem at all, as long as there is enough room for everybody. All the more so if you have your rows running north and south, as is preferable anyway.