OK on your confidence in the sealed plastic. From a guy who has CaCl spread on his gravel road to settle the dust, you'd be surprised what that stuff can pull out of dry air. Road looks and acts wet. NaOH, another hygroscopic salt is also a pretty common occurance.
However that may be, thought I'd get in a whack at conventional wisdom and offer up some ideas on lathe weighting. Yours is the more common "weeble" approach, where it may wobble, but not fall down. Convenient to put the weight centered under the axis of rotation and all, but there's a better way. Look at the diagrams attached. Before the engineering types jump in, yes I know that the perpendicular to the tangent should run through the axis of rotation, which makes the "equal and opposite" out of line. Bear with me, it's simple thinking. Those who want to get more complicated can look into
http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html and update themselves on angular momentum and such.
The place to put the weight is the place farthest from the axis of rotation, to increase the moment of inertia, and to the rear, because the tangent vector indicated at ten o'clock wants to do two things, compress the front leg, which it can't, unless you have rubber feet, and lift the rear leg in one of those equal but opposite reactions. How far out should the front legs extend? radius plus perhaps 20% should work.
Those interested in stability should realize that the moment of inertia varies with the
square of the distance from the axis of rotation, then, in case you have a heavy spot far from the center, remember its energy varies with the
square of velocity. If that doesn't make you want to trim things up as well as possible prior to swinging and start as low as possible, nothing can. All this load, plus others, is taken on your bearings, and possibly on you if careless.
