For the past 12 months I have been using "double screened twin feed digital cable" in my caravan. This double/twin cable does away with the need to have two seperate cables from your dish to the van, much tidier and less chance of falling "AoverT" over yards of cable.I bought it from Melksham Satellites Ltd who have provided a top class service with everything you need for receiving satellite signals. The link below will take you there for a look-see. Best of luck JTS.
http://www.ekmpowershop2.com/ekmps/shops/melksatltd/cable--clips-43-c.asp
http://www.ekmpowershop2.com/ekmps/shops/melksatltd/cable--clips-43-c.asp