The bigger the trailer the more uses it will have but the harder it is to be stored. People with light fingers really do love a trailer. Don’t expect to own it for long if you just chain it up on your front yard.

mk3 Mondeo will mostly tow a max of 1800kg braked and 750kg un braked but there are exceptions like the st220.

If you like a bit of Diy then the capacity to take an 8’x4’ sheet is a plus. If it’s just for the tip run you won’t need brakes. A second hand galvanised trailer like Halfords sell is ideal and will still be re sellable if looked after.