Just some follow-up info for anyone interested in the same accessory.

Since I had seen a tether and anchor on the GoWesty site (in the pic
for the Recaro car seat), but couldn't find an anchor kit, I called
them up. They do sell a kit that looks appealing (not yet officially
on the site, but soon to be:  p/n GVW-TETHER-KIT).

It mounts to the upper part of the rear hatch frame - the tether is
fed through a hole one needs to make in the upper rear shelf. I kind
of like this because it preserves room for packing things in the back.
That is, the tether doesn't interfere with the rear cushion or deck.

Ron Johnson
Portland, OR
'91 Weekender, "Betsy"