WOW!! You'd need a tractor or lorry to tow it!!! This is the biggest trailer I know of: http://www.iwt.co.uk/products/horsebox/hb610?tab=details but is for 2 x 17.2 OR upto 5 ponies, it's payload is 2050Kg, so nowhere near even 3 x 17.2!!!
I know that Fautras Promax 4 make them and also Pegasus... I have the vehicles to tow them, I just need a contact number for someone who actually sells them... I know a woman in Kent has one and uses it all the time for shows, but she bought it privately... someone somewhere out there must know some )
Competitiondiva: I have a variety of vehicles, the most suitable one would be 3500MGW for the lead vehicle with a total train weight of 5500kg.... which means I could tow pretty much any trailer as my lead vehicle is 1400kg at the kerbside. I just need to find a lightweight trailer to do what I need, so far the best one I think is the Ifor HB510XL as its unlaiden weight is 1290kg, leaving a 2210kg payload... thats almost 3 horses at around the 750kg mark.. this is what i am looking for i think... now just need to find one for sale!
Was going to say Fautras but Cheval Liberte do one too.
Cant imagine what would tow it with 4 big horses though. I thought even a Range Rover only had a max towing capacity of 3.5t.