Anthony... I am currently building the Polaris and I have an on-going build log available to follow somewhere on this site. This build is my 1st plank on bulkhead model. I am moving at a relatively slow pace as I have other things to attend to but I try to post to the log when I can. You will probably surpass me in the build and I may be coming to you for questions.
As to the loose bulkhead slots, I didn't find it to be an issue; HOWEVER, I made certain the bulkheads were square to the keel. I also dry fitted the deck to the bulkheads before I glued them to the keel to make sure the deck would fit into the slots.
You'll find that you may need to deviate from the plans (and video) from time to time instead of blindly following the instructions which may lead you into a corner. So think ahead several steps or operations before gluing up.
Just my 2 cents worth. Other more experienced builders may have additional / alternative inputs.
Good Luck with your build. I look forward to your progress.
...henry