your problem will be tongue weight/payload.
the 700lbs. tongue capacity is calculated with only a driver in the Nissan. you have to subtract the weights of passengers, cargo and WDH from that.
the 21SS has a very heavy hitch weight for its size. dry is 570lbs. my 23SS has a dry hitch weight of 458lbs. and it is actually around 600lbs. loaded. so, the 21SS has the potential to easily be over the 700lbs.
the 23SS is actually more within the Nissan's specs, than the 21SS is.
SUVs tend to have much lower tongue capacities due to their softer suspension.
and Zoe the Wonder Dog(R.I.P.)
'07 Roo 23SS pushing an '07 Chevy Avalanche
Equalizer WDH and Prodigy BC