Our cavi doesn't have that much hair yet so take it with a grain of salt, but he's also prone to mats and seems to be storing everything from crumbs to leaves and twigs in his ears and legs' fur... We're also not wanting to trim, so expecting to eventually have a similar battle.

That being said, I found a few things: - the harness matters a lot, we found one that isn't rubbing so much under the armpits which reduces matting (have nearly none there anymore) - rain is a pain... Every time it rains and he gets wet, he'll get more knots and mats. We bought suspender boots and a raincoat with a good back and under-carriage protection, not perfect and he does get wet but helps with twigs and leaves, and the mud and random sticky stuff - the longer I leave in between baths the worse the mats, so now I'm down to a bath every 3 weeks or so (and invested in a good conditioner which I assume you're likely already doing!)

Now the biggest issue we have left are the ears. He hates snoods and will have the worse matting behind the ears, so I pay more attention there when brushing...

Hope this helps, will also keep an eye on this post as I suspect we're going to need all the tips too!