TV co-ax plugs are known as Belling-Lee after the company that designed them: satellite connectors are known as F-type. You can use F-type for TV but you can't use B-L for satellite.
I would suggest two things: first that you convert all of your connectors to F-type - they are much more secure when fitted. Yes you may need a B-L plug or a F to B-L adapter for the connection to the TV buts that's all. You should use PF100 cable or similar that has a copper foil as well as the braid to reduce pick-up along the cable.
Second, fit your van with a fixed connection. You can get a F-type back-to-back socket adapters which are designed to be fitted into a bulkhead. Drill a hole of the right size through the (internal) side of your battery box, install a cable as appropriate inside the van and connect it to the inside half of the adapter, and connect your external aerial inside the battery box to the other side of it. No more windows seal problems.
You can see the connectors and/or adapters in Maplin, but buy your kit from Toolstation or Screwfix at a fraction of the price.