Hey Paul, I've given this a little more thought. I've remembered that, in the distant past, I've used a rear mounted rack on a glass edge rear hatch by using the rear cross bar from a roof bar set as the anchor point for the main weight bearing upper straps (those that would normally attach to the leading edge of the boot/hatch). Then you just need to check that the rear bumper is strong enough to take the main weight of the bikes. The side straps and the lower straps are there to stabilise, rather be load bearing, so they don't take a lot of weight. Certainly on a Mk1 there are two towing eyes below the bumper that would be ideal for the lower straps. The side straps would just need a bit of gaffer tape on the edge of the glass - unless you start throwing the car around they don't have too much to do. A Thule roof bar takes five minutes to put on or take off, so pretty practical. I used a Halfords high level bike rack (gets the bikes above the number plate and lights) and this arrangement was stable enough for three bikes on continental driving holidays. It may look slightly unconventional, but easier/cheaper to source than a C1 towbar and an assisted lift bike carrier
