Switch forward rules on-the-fly?

Hello

I use a text browser with Tor quite a lot and often come up against
captchas. When this happens I usually go through a different proxy,
but then I lose the privoxy protection. It's either that or boot X11
and a GUI browser, find the site again and complete the captcha.

Is there a way of switching from one proxy to another somehow via my
browser that doesn't involve turning off privoxy or adding a rule for
each site that this happens with? With my regular sites I do add
rules to go direct or via a plain http proxy, but I don't want to do
it for every random site that uses cloudflare etc., which seem to be
on the increase now.

I'm kind of thinking something I could add to the URL to let privoxy
know that I need to use a different forward rule. I looked at tags,
but I'm not sure I really understand if they could work for what I
want.

Thanks for any help.

--
Az