That's what I did with one of my Kraits. The build is in the thread in the ships subfourm. One cool thing is a core mining ship just needs two medium hardpoints for the job, leaving the rest for weapons, allowing me to engage interdictors and put that to a stop, quick.
For me I go for LTDs, yeah, but I'll mine other stuff. I don't much care about stuff like credits per hour. Over the past few days I've read two threads debating what is the fastest way to mine to get the maximum credits per hour and one about credits per hour in exploration. I couldn't care less about that. Core mining's cool. I like it. I don't mind if some of my hold is filled with suboptimum ore or minerals. So VOs, alexandrite, or other well-paying fragments are fine. If the LTD hunting is slow in that particular ring I don't mind going bird in hand so that I'm not trying too hard.
My mining Krait's hold is 128t. A full load of top-pay LTDs is 204 million. But making half of that is fine too. I've already got way more money that I'll need, so maximizing it all just to get more isn't really the point. I just do it for activity rotation, constantly switching up what I am doing so it takes longer to go stale.
Building a dedicated miner is a really good idea. It's the one role I do that requires the most conversion of a non-dedicated ship. Gotta install a refinery, and a pulse wave, the blaster and seismic charges, prospector and point defense for hatchbreakers. Once that's done, I want to re-do priorities and then it's necessary to re-do the fire groups. So that's a lot of work converting the ship over to mining. So much better to have one always ready to go. And beyond that, it allows you to whistle for it anywhere, arriving fully kitted out for the job. No need to fly to where your mining modules are stored.
So yeah, that's a longwinded way to say a core mining ship is a fine idea