I just got off the phone with Stormwise, intending to order another 18" "Monster" ferrite, since I have a few other ideas about what to do with them. As it turns out, they are available in 2" increments, so I special-ordered a 24" inch model of the 800u permeability type (Model VFR24J). I think they're all made to order, so it's just a matter of him telling the fabricator how long to make it.
He wasn't exactly sure of the price, likely $10 or so more than the 18" (which runs $33.75), but he'll let me know as soon as he gets a firm price on it. So, in about a week I should have an even larger Monster ferrite on hand, which I will likely devote to longwave with regeneration.
Looks like I'm going to have to find a longer backpack for my morning commute DXpedition gear...
Bainbridge Island, WA