I live in Aust. and I'm 5'2". I didn't like the idea of struggling with my bike to get it on top of the car, plus like many Australian homes, mine has a carport and I felt sure I'd get home from a ride and forget I've got the bike on top and crash into the ceiling. So I bought a Thule EuroWay, same as Thisle

Thule EuroWay 945/947
http://www.thule.com.au/products.php (click on towbar mounted)
It's one of the best accessories I've bought. I can load it up and put my bike on myself with no problems. It's got the electrical fittings right so when it's loaded on the back of the car, your braking/indicators are 100% visible. Big plus is that when it's loaded up and you need to access your hatch, you can tilt the whole contraption with one lever and you can open your hatch. I bought some locking nobs as well which replace the clamp nobs for the top tube. This way, when my bike is on the rack and locked, no-one can remove it, or any bike behind it. My husband is very careful about his treasured carbon frame bike and he reckons the clamping of the top tube is gentle and that the bike stays firmly secure because the weight of the bike is supported by the base and held safely by the wheel straps. Unlike some racks where the bike is clamped by the top tube and that clamp takes the weight and that can damage a carbon frame.