Improving my port – building and draw distance

I'm working on a wooden pier. I know I could build a "better" one by raising the ground, but if I wanted a standard wooden pole supported pier, what is the best way to build the underwater supports. I start by building out and then down in order to keep everything lined up correctly, but it's hard to get the support poled to snap beneath the previous one. I've managed to go down 2 by building a couple of guide poles on one side and then sliding the next core wood pole under that one. But once you're close to the bottom, that doesn't work. I've been able to go slightly down further by laying some stone supports on the ocean floor beneath my lowest pole, but that only buys a couple of feet.

Switching to iron reinforced wood (overlaid with corewood poles for the visials) got me a little further out to sea, but also made the stone block supports less useful. There's no good way to lay those once you're on the lowest floor you can build without floating.

Is there a trick for building down?

And second question, which probably requires a mod or (at least) editing an ini. Is there any way to increase draw distance beyond the max in settings enough to make my lighthouse be useful for navigating at night?