Just a warning that while a rail may be helpful for you, it doesn't entirely solve the problems of close-focus composition. It will allow you to make fine adjustments front-to-back and side-to-side, and it will give you an alternative way of making the small focus adjustments needed for stacking. (In my experience, the latter isn't needed for work up to a bit more than 1:1; turning the lens barrel works fine. At high levels of magnification, however, the greater precision of adjustments with a rail could be very helpful, and some expensive rails allow one to automate specific changes in focus.)
What a rail doesn't do is allow you to make fine rotational adjustments--rotating up or down, rotating side to side, or tilting the camera. In coarser work, these can all be done fine with a ball head, but the slop in a ball head (e.g., the sag after releasing the camera) is too great for close-focus work. One can get the framing one wants, but it can be frustrating, time-consuming, and approximate. I use rotation on all three planes all the time in doing studio macro.
To get fine control over rotation, you need a geared head. Unfortunately, as far as I know, there aren't many of these, and they are expensive. I use
this one, with a Hejnar adapter to make it arca-swiss compatible, but it's really expensive. Perhaps with some searching online you could find either a cheaper one or a used one.
This is not a reason not to buy a rail--just a heads-up before you buy one that a rail will still leave you will some framing difficulties at very close distances.