Just an idea, if you really want to see the value in some sort of UI, you can make a custom status (well bunch of them) that will represent the level of mining.
So if you don't plan have mining lvl 99 or something similarly crazy, but will have something like Mining 1-10, you can create statuses lvl 1-10 in stat editor and permanently apply it your character, so it will always be shown near the portrait. It is a bit of manual work, but then you can store them in database and clear/assign as your char progresses.
