I had my wiring for outlets, sconces, over head fan and ceiling fixtures all done before mirror, fixtures, vanity and cabinetry were added. I have a small oval tilting mirror that is only 24 wide over my vanity it was dirt cheap from lowes and they had rectangles too. Under 100 dollars. Your contractor should be able to drill with a new and properly sized drill bit to tile without issue and if it cracks the tile can be easily replaces. I know cause glass door guys broke a tile on their last hinge using a dull unchanged bit and my tiler fixed it is less than an hour. I can not attest to its quality but I love my cheap I mirrors function. This is similar to mine might be too short at 24 I think. https://www.atgstores.com/bathroom-mirrors/gatco-elevate-small-rectangle-mirror_12643290.html&ppc=2615&af=2615&cm_mmc=sce_google&s_kwcid=AL!4500!3!112410639507!!!g!189703215387!?gclid=CIyj4OfV0M4CFUMkhgodpYQGxw&ef_id=V2mUpwAABYlpJA92:20160820185548:s

Here is your dilemma. if you take down those fixtures there will be two holes in the mirror, that being said, they will be up high and most likely off center. So, to get new lighting that is not stuck in the corners, and covers the holes behind it, might be next to impossible unless you run a thick bar that covers the space. But some times back in the day they only drug wire over and did not put in actual junction boxes, so the bringing it to code might be another issue. 1. take one of the lights down and see what is going on 2. probably have to replace the mirror and move the electrical location.

https://www.houzz.com/hznb/photos/contemporary-tiburon-home-contemporary-bathroom-san-francisco-phvw-vp~2864264 This is the look we are going for

Thank you so much for your help! We actually do need the tower for storage as the bathroom is not very big at all. It currently has a bulky built in linen closet on the left hand side of the vanity and the current vanity is even smaller (60") that my husband and I have shared for 10 years. So while I'd LOVE more counter space, even the extra 9" we are gaining feels like a lot for us. We put the tower on the right because it is next to the wall when you walk in the door which keeps it from being in the middle of the room breaking it up. It helps that the top part of the tower sets back on top about 6" from the facing of the lower cabinets to make it feel less intrusive. I am concerned that a 3-light fixture may make it feel more congested, but I just don't know as it seems there would be room for it.. Is more light better or would a 2-light be better for scale? I do love symmetry, and you have no idea how much it pains me to not have a perfectly symmetrical vanity.. But it really is the best option for the space due to how tight the bathroom is as a whole. The tub is directly in front of the vanity (about 4.5' walking space) which also sits in front of a window providing a lot of natural light in the room.