Param to get more results in RSS feed

I just stumbled on a way to get an RSS feed of a tag but am unable to get more than 20 results. Is there some useful RSS feed documentation lurking somewhere in these forums?

Here's an example URL:

>> https://community.lithium.com/lithosphere/rss/search?q=tags:tag

I've tried adding:

&page_size=100
&limit=100
etc...

Nothing seems to have an effect.f

Separately, this RSS URL only seems to work for tags without spaces.. if anyone has ideas on that it would be greatly appreciated.