If your ratchet straps are listed for 1k lbs each you are more than good, i've got some that are rated for 800 lbs each and use them to strap down my Rhino and Argo, never had one come loose or break. Make sure to keep the ratchets lubed, I use PB Blaster to keep them free of rust and grime and clean them about once every 4-5 trips.
