I bought a 4ft that extends to 7ft for £40 from polarbrite.
I didnt have it installed at grimsby but they told me, to have it installed would cost about £600
I wouldn't bother with a 13ft, if you want it for everyday houses get a 17-18ft pole.
I have my tank strapped to the van with 2, 1 tonne ratchet straps. those straps will not snap as the tank when its full will only weigh approx 370kg.