need a tow bar fitted

There’s one down Dorset/Hampshire way but I can’t remember the name. He’s used to dealing with the Alko extension chassis. Google is your friend.

Mobile fitter?  Obviously need to check they fully understand what exactly they are fitting the bar to, and what for - bike rack? towing car?  towing caravan?  But I am sure you could find someone who will fit it on your drive, or if a secure storage site, with their approval.  

The problem is caused by the Alko extended chassis, wh1n, as the towbar has to be fitted forward onto the original chassis. Not all towbar fitters are able to do that. Sometimes water or gas pipes and water tanks can be in the way so towbar fitting can be very complicated.

I note no one is rushing to help. You could try indespension - they fitted a tow bar for me at a very reasonable price. Unfortunately you may have to travel to the midlands - Worth a look

I think we've all helped in one way or another, Toby, but the OP hasn’t been active on CT since he started the discussion so our words apparently go unheeded.