I've been thinking about this issue, as far as the tattoos on the legs, as you had said earlier, don't choose the length of your dress based on this issue.
You could try a cool pair of tights/nylons that have a design that goes along with your tattoos??
You could make them yourself, may need some help. ( put them on and then have someone help draw or what not on them.... make sure its when you can scrub scrub scrub afterward though..
pick out a pair to try it out with.
You can embroider them, or paint, or use sharpie markers, or glitter glue...
as for the tattoo on your upper back...if you chose to wear a veil that would likely cover it enough.
Again you can craft it up to tie into the design of your tattoos so that it's hardly noticeable at all.
If you do not feel that you want to try and tackle this task, you can find a local bridal or tailoring shop, they would likely be able to complete this task for a fee of course.