Towbar - electrics

[super__dan]

I know this is a bit random but some informed guys on here....

I'm planning on fitting a towbar for some VERY infrquent use of a caravan (like may get used 3 times in total). Bearing in mind the amount of use and also that I'm tight I've got two queries regarding the electrics.

Do I really need the 2nd electrical socket for a caravan? I'm not bothered about charging the leasure battery or running the fridge whilst driving as such I'm considering only getting a 7 pin for ease and it looks less 'bad' on the back of the car.

Bypass relay - How do you know if this is 'needed' or not. I take it that if you use the relay the wires in the lamp cluster become effictivlye signal wires for the caravan rather than actually powering them and are therefore more reliable? The relay itself is seperatly fed.

Anyone got a used one for a Mk2 Focus hatchback 2.0TDCi let me know ;-)

Cheers,

Dan