You mentioned it would be you going by yourself 90% of the time. In a lake that is primarily used for fishing, that’s probably a bad idea. The viz will be near zero. You will run into sunken tree limbs, fishing line, rope and other debris that could easily snag you. And since you’re new to diving, a simple snag could mean death.
If you get caught on something, you’ll initially freak out. You may end up freaking out so much that you forget the simple things that can be done to save yourself. The more you freak out, the more air you use and the more you want out of the water. It’s easy for an inexperienced diver, who is diving solo, to get caught up in a situation like that.
Not to mention you’ll be leaving the boat without a captain.
I would recommend you dive with a buddy at all times and leave one person behind to watch the boat and act as surface support. I don’t mean to scare you, I just want you to be aware of some safety concerns.