Hi mate,
I am in the market for a new heavy duty off road hitch also, after just completing a full rear fold camper conversion on a ex RAAF Track Trailer.
Look like I will be going with a McHitch 6ton set up. Kedron caravans are running with these on their off road models & are getting great feed back.
I have had a close look over these in Kedron's work shop & the hitch appears to very well Engineered, with spare uni's available at any outlet that sells Toyota parts.
Good thing about these is it is a lot easier than other hitch's to hook up when in tricky situations.
The 6 ton hitch's are not cheap so big call!
Refer link
6 Tonne Coupling [6TON] - $795.00AUD : McHitch.com.au - Uniglide Trailer Coupling, Shop