Just to clarify... by 'Jack-up' are you reffering to a lift kit or is this a 'Using a Jack to lift the truck up' type of question.....
AFAIK there are still lift kits for pathfinders... I would check with Calmini.
As for using a hi-lift Jack under the plastic bumpers.... That may not be entirely advisable...they can tend to scratch the paint
Hi-lift does make some attachments for lifting vehicles with curved bumpers though....like a kind of hook deely with a chain and Jack adapter...
You can usually lift off of the trailer hitch in the rear though (if you have one...)
If not.... You might think about getting one... they can be really handy to have as a recovery point in the rear of the vehicle.
( I'm talking about a reciever hitch style here...)
Yes, with the '96 and up Unibodys, the only lift available is the suspension lift. Automotive Customizers has them too.(www.4x4parts.com check out this Nissan board for all your Nissan 4x4 questions and discussions too) They are coils that will give you 2". You can fit 31's without the lift but there is some rubbing at full flex.