Are there any defenses I can put in front of my websites that are good for stopping these things? The amount of traffic I see from residential proxies is just killing me. In particular defense against residential proxies.

Make your server so efficient that a few extra requests doesn't bring it down.

Alternatively, if it's the first time the IP is seen and it's a deep linked page with no referer, send a neverending chunked gzip data stream.

The bots used by these proxies are detectable in a few ways. Remember the bot itself doesn't run on the proxy...

There is discernible lag from proxy to c&c node. The individual bots don't have access to a lot of compute, and are sometimes restricted wrt feature set (e.g. proprietary video codecs).

There are a few other techniques. It's a cat and mouse game though. And the bot owners are usually more motivated than you are.

Add a captcha or proof-of-work challenge in front of your website. Those are pretty much your only options.