I would just run one tube and block the other off personally. At least for now. I know you were hoping to have pole breathers though but seriously... at this point, I think getting on the water and enjoying the ski before it gets cold again should be priority number 1. Three months from now, you can change all the stuff that you wanted to do and either didn't have time, money, or motivation to finish. After a few rides, your priorities and things you want will change anyway.
Just make it work so it won't break down on you every ride and go have some fun... If you're frustrated and broke by the time you finish the build, you won't want to ride it because you don't have the motivation to tweak it.