I'm not sure how easy it'd be to achieve either A or B; the only real recommendation I can offer is to upgrade to UBB.Threads7.
UBB.Threads7 was recoded completely from UBB.Threads6, UBB7.1 comes with a CAPTCHA system which is a quite simple way to filter out spambot registrations...
In UBB.C6.7 I was plagued with spam, so much infact that I was planning to go to a differant product when both Threads and Classic where announced as being EOL and dev on 7 ceased last year; but when dev continued I was quickly one of the beta testers to help with some spam prevention and it worked flawlessly...
I went from about 30 spam messages a day, to 0 per month...