The runners installed (by manufacturer) on my boat are on the toe rail. The tang is through bolted through the cap rail and the hull/deck joint. The athwart (transverse) placement is therefore maximized, as is the case for every other example that I am familiar with.
You do not mention boat size, but 5-ft aft of the mast sounds very
close. In this picture, you can make out the tang for the runners just at the base of the stern pushpit - on the cap rail. On a 40-ft boat, that makes the distance more like 12-15-ft from the mast.
The runners are only deployed to support the mast when the inner forestay is used because it attaches well below the mast head. The universal pain in the ass with runners is, of course, that they inhibit the boom when tacking (or gybing). One must be slacked and one tightened for every change of course.
wrt stay storage; I assume you mean a "convertible" inner forestay on which the sail will be hanked when deployed. Mine is stored on the mast. It lays in a notched and radiused fitting at the base of the mast. It doubles back up the mast and then secures via its end-shackle to an eye on the mast and is tightened via its integral turnbuckle
. The radiused fitting assures a reasonable bend in the wire. It has shown no damage or deformity on inspection (or very infrequent use) over the years.