HTL, Jon has one of my test vats that is the self-sourced LIttleRP2 style
http://imgur.com/a/yoYyl and the underplate does have perimeter venting, it does not have the raised masked edge that your current V5 testing vats do however. The vat is running low tension on it as in my testing I have found the higher tension can contribute to uneven layer lines with the part shifting due to higher stresses of a shallower release angle, however at the cost of lower film life, risk of localized distortion etc.
Jon, if you add a base "add sole base" option and reprint does the part fail in the same place?
I think the issue may be that the FunToDo is harsher to FEP than some other resins, it definitely destroys PDMS and that the film may have lost some of it's non stick qualities from simple use. The small attachment base in comparison to the flared feature on the part simply can't hold on in the presence of increased stickiness of the film + larger cross section of the part. You are just seeing the issue earlier on in the life of the film as there was less margin to begin with, so not saying the film is toast, but that the part likely needs better adhesion to the build plate, either through perforation / roughening or more surface area on the bottom of the part (CW base support).