Hi Dan
I haven't fitted one to a Dispatch, but I have fitted a couple in my time.
Everyone came with fitting instructions which are fairly easily to follow. They have any additional brackets you will need to fit them and they fit into existing mounting holes. The Relay that I have uses the rear spring mounting bracket as the main fixing point, so some bolts had to be removed and replaced with longer bolts. I always assemble any bolts with copper grease.
One thing to account for is that these towbars are quite heavy. I put a jack under the Citroen Relay one I last fitted to fit it into position. Most mobile towbar fitters put the back up on some ramps to make access easier, but that also means that you have to support the weight of the towbar while you fiddle around trying to get bolt holes to line up properly. You will need to just get the bolts to hold with a few threads until everything is in position and slowly tighten the bolts a few turns at a time. You must do it properly as they inspect it's mounting spots at the time of MOT test, especially if the vehicle has a bit of rust underneath.
Not difficult but you need to allocate a morning to have it complete. The electrics will mean tapping into the rear lights and you will be given a universal electrical diagram to couple the socket to. The idea is that you will be able to tow any trailer in the country. The pins on the socket are numbered so if you work carefully, you shouldn't have a problem.
I would invest in a little tester so you can identify which wire is which when you are coupling into the tail-lights clusters if you haven't one. I once brought a probe which has a sharp point on the tip with another wire to earth. By pushing it into the wire through the insulation you could easily find out which wire is which by not damaging the insulation. You could do the same with a pin on a 12 digital tester but you would need to make sure you didn't touch the body which your contraption by mistake.
If you have parking sensors then you must be aware that the towbar will be seen by the sensors, setting it off everytime. In cases like this, you need to fit a more expensive detachable towbar. (Towbars are expensive these days, so please don't be tempted to buy secondhand. Chances are that you won't get all the brackets and you won't be able to replace them individually. You also won't know the towbars history. If the vehicle had been in an accident, you won't know how safe it is either. All bolts will be high tensile.)
A towbar is classed as a modification and will increase your insurance premiums as the insurers see towing a trailer as an increased risk, so if you don't need it, don't fit it.
In South Africa we always fitted a towbar as it afforded some additional protection in case of a minor bumper bashing accident. I had a towbar on the back of my Mitsubishi Tredia with a large steel plate bolted behind the towball for stablisers for towing our caravan. A new 3 series BMW ran into the back of me at some traffic lights - no damage to my car but it made a mess of his BMW.
