Are you in UK ?
On the hitch different ball sizes are available in uk,
most 4x4's in uk will pull up to 27ft and the older the trailer the lighter it will be.
on the 220v a good stepdown transformer will do the job with a consumer unit, but not a builders yellow type
on the waste, most european trailers use cassette toilets, and grey waste into a "waste hog" which are a about 40ltrs,
on my overlander i still use the main fresh water tank though.
Hope this helps