I would think they would have no trouble at all. They would come up and say "What mulch?"

I guess my only concerns are that such high mulch will encourage rodents to knaw on the covered canes over the winter or all the added moisture will cause a rot of sorts. Can brambles get any crown rot? I'm assuming no since they seem to sprout roots from anything touching soil...

Thanks

Well yes they can get crown rot. Both are valid points. Maybe use a per-emergent instead.
One organic one is a corn meal of some sort? I don't know much about it? It's expensive though and with 300 feet, a conventional one is more in line.

U-pick caneberry fields out here are commonly plowed between rows, and heavily grassy right in the raised row, year after year. Large weeds with deeper root systems should be kept pulled.

After 3 years you should be able to tell if your caneberries are competing well with the grass and weeds.

Mulch is a berry good thing.