I've just fitted a towbar for the same reason, i wanted to carry my bmx and DH mtb. My old car, a
mk4 ibiza got wrecked due to me throwing the bmx in every day. Couldnt have the same thing happen to my new pre-facelift
cupra so decided to go with the towbar/bike rack idea. As far as i'm aware with every towbar your are gonna have to cut a hole in the bumper.
I fitted the tow bar myself, there are two main types, a permanent and a detatchable. On the detatchable the ball arm of the towbar comes of allowing you to place a cover where the hole is left. I've never really worked on cars and it took me about a day all in all to fit. The time was taken up mostly by me not being able to get the trim inside the boot out, and then once getting the whole thing back together having to take it apart again as i forgot to wire the number plate lights back up. Idiot.
The towbar i used was this
one.
I would take pics but its exactly the same as this one recently posted:
http://www.seatcupra.net/forums/showthread.php?t=172192
This is a
guide for bumper removal on a pre-facelift
cupra:
http://fallenangelxsi.piczo.com/?preview=y&g=24212843&cr=2&rfm=y
If you do a search in the forums you will find a lot of threads on this. Though not many of them are very usefull. The best one i find had this link in:
http://www.simonranson.com/SeatLeonFR_towbar.htm
Very usefull if you do decide to fit the towbar yourself. It also shows a detatchable tow bar.
The bike rack i bought was the thule 9403:
http://www.bikerackshop.co.uk/thule-9403-ride-on-bike-carrier-racks.htm
Can pick em up for a £100 if you scour the tinternet. Thats for the 3 bike one mind.
I can get some pics of the car with the bike rack on if you wanna see what it looks like.
chainreactioncycles.com also have a few other recomended towbar mounted racks. The thule was the cheapest option really and i had heard good
reviews of them.
Hope some of this helps