Can you tow with and MX5 in the UK? The simple answer is no. On UK MX-5s the train weight is blank which means the max allowed towing weight is zero.
On Japanese imports (Eunos Roadster MK1) the story is different as the towing weight isn’t marked on the sticker, so you can get away with using one for towing (this is a debated topic and it is not 100% clear).
The maximum you could tow is half the cerb weight of the car, so under 500kg. I have seen lots of forums saying maximum is 750kg for unbraked trailer, but this is wrong, this is the maximum for your license, not the maximum for thr car. Also, make sure that you check what your driving license allows you to tow as the law has changed over the years. Towing: licence and age requirements - GOV.UK
Personally I would not want to tow 500kg with a Eunos Roadster with standard breaks or standard clutch, as I just don’t think they could take the extra forces.
I have found a great quality towbar for the mk1 that can also be used as a rear jacking point, similar to the DaveFab one. The great thing is that you can remove the tow ball easily, so you can’t see it is fitted. Towing Brackets for Imported Vehicles : Hand Built Towbars : Watling Engineers UK it is easiest to give them a call as you can not order from their website.
Even if you can’t tow, sometimes you need a little more cargo space. I have boot bags and have used boot racks, but both can mark the paintwork. So my solution for camping holidays, and taking the club gazebo to car shows etc. is a tow bar mounted cargo rack, you can also get bike racks that mount in the same way.
I have the buzz rack P10, and I have to say I am impressed, great for bulky lite items up to 75kg BUZZ RACK Buzzpro P10 multi-purpose tow ball platform no. BRMP01. as this is not towing, there is nothing in the law to stop you doing the same.
I hope this information is useful for others needing their five to be a little more practical. Please do your own research, as the above is the best information I could find, but you will need to satisfy yourself that you are not breaking the law.
Note: don’t forget to add a light bar of the rear lights of the car are not visable past the load you are carrying.