Your suggestion is a good one. In somewhat related threads, users have asked Singular Sound to sell the PSU separately (as does Strymon and other pedal vendors) but SS replied that they don’t sell just the PSU. Therefore it’s a pretty safe assumption that they won’t sell the barrel connector or an adapter separately. A link to the adaptor specs is at Custom Power Cable
Some users have posted finding a switchable adaptor from MyVolts. You can search the forum and contact that vendor to see if they’ll sell just the adaptor. This link has several suggestions such as the Strymon angled adaptor and a link to MyVolts Beat Buddy Power Supply Update - #41 by Blowback
Please share with the forum if you find an adaptor that works for you.