If your van has an external battery box you can get an F-type 'barrel' which is a socket either side. Drill a 9mm hole in the side panel of the battery box and fit the barrel into it - it is threaded and if you get the right one it comes complete with nut and star washer. Then attach a cable on the inside and run it to you TV location. You can then use the socket in the battery box to connect to the pillar, to an external aerial, or to a satellite receiver - the connection is compatible with all three.
If the battery box and TV are not located such that you can get a cable from one to the other easily then the only other practical option is to have an external connector box fitted - or do it yourself. They are not difficult to fit, require one hole through the side of the van (and two lead holes for the mounting screws) and the back of it has a soft water seal so if it is fitted carefully it will never leak. I had one on our last van and it was great. It has the advantage that it has two spaces for sockets - one for TV and one for satellite - and it comes with two appropriately terminated cables about 3m long.