<VV> ISO advice on towing convert

[Barbie]

We like to take our 62 Monza convert on vacation with
us but she's not very comfortable for our old backs so
on long trips it's nice to tow her.  We've rented
carriers from U-Haul twice now to do it.  The first
time we put her on backwards to keep the weight at the
front and it was very stable but caused the top to
tear at the rear window (old top we wanted to replace
anyway, gave us an excuse to do it).  Now we have a
nice new top so this time we towed her frontwards and
it wasn't bad most of the time but we could tell there
was great potential for fishtailing (I know, I know,
put sandbags in the trunk...).  Does anyone have
opinions/advice about tow bars vs. dollies vs.
carriers?  We might want to buy something of our own,
possibly even a covered carrier some day, so opinions
on those would be nice too. Also, is it possible to
have a cover made of lycra/spandex that would be
form-fitting enough to allow a car to be covered when
on an open carrier?