I have done a lot of searching on this website, Wordpress.com, and Google, and that i haven't found a solution, so I'll try posting here! Whether it's recently been clarified, I am sorry ahead of time for my search-fu failure.

I operate a podcast and blog utilizing a WordPress/PowerPress combo. Due to the limit on many aggregators, I must keep my site's primary feed under 512kb, so I have limited the amount of posts that demonstrate in RSS to 50. However, we regularly get people requesting an rss feed which has our entire catalog to allow them to pull lower our show's full history.

It is possible to wordpress plugin or some feature in WordPress that will let me leave my primary feed using its length limitations but launch a parallel feed that shows everything? Or it is possible to easy trick I'm able to do within the PHP?

Thanks ahead of time for just about any help!

Why don't you to create the 2nd feed yourself? WP Codex