As far as I know, the reason of SMTs not being able to Power Down to less than 13 weeks has nothing to do with it "circumventing the base token" but everything to do with Steemit Inc. not yet creating that feature since they want SMTs to be released ASAP.
As far as I know, shorter timeframes will be possible with future SMT's, even if Steem's Power Down time remained 13 weeks.
P.S. I brought up the SMT issue since I read in one of your comments that it is one of the reasons why you are in favor of a 4 week Power Down for Steem 👍