This is possible, it has been tested with a total coax length of 30 meters.
However, the following matters are important here:
The coax must be of good quality (no thin coax, otherwise too much signal loss will occur)
If you use an external external connection on your caravan /motorhome, you must also include the internal coax cable. If the internal coax is of a lower quality (thin core), this is an additional loss.
