I haven't read the other post responses yet. I think you've made a lot of thought towards what you need to do, and only you can decide what the right thing is to do.

I would caution you on your thought process regarding the CDL. It sounds like you want something that will make you marketable for the next job. And you want them to pay for you to do it. I'm not sure they would want to do that --- in other words, if you know you're definitely out, you probably should stop with your CDL training as well unless you're willing to pay for it yourself because it will make you more marketable. This would be like adding a certificate or a master's degree to make yourself more appealing to the next job. I would assume most, if not all, districts would not pay for your advanced degree just so you can use that training for the next gig. They are looking for a return on their investment.

If you're not entirely sure if you want to leave or not, continue with the training. If you happen to make up your mind once the year is done, you should be able to resign from your contract by late June or early July. At that point you could justify to the district you weren't planning on leaving but another opportunity came up after you completed your CDL work.

Furthermore, just because you want to leave doesn't mean another position will want to hire you. You may apply and ultimately not get the position, even if you have glowing reviews from your HD or admin. Would you return for year 3, or leave the profession altogether? Typically it's easier to get a job teaching if you have a job teaching.