You can buy one in good nick for that at the moment. Actually, you may have missed the best time as people unload them at the end of the summer. They fester in garages at the moment and will prolly come up for sale again as the days get longer in feb/march.
I guess There isn't a whole lot of luggage space, it's better if you forego the spare (or carry it on the boot rack). I've no idea how big a
60l rucksack is.I got my mate's girlfriend in the boot of mine, she's about 5'6.
I saw someone who fitted motorbike top boxes to his boot rack so he could detatch them in no time and carry them into the hotel.