[mik]

that`s what i would have gone for also bushy,
if there is room to fit the plain old air shockers on your model Cam, much less mucking around i think,
if you want to get really snazzy you can buy an aftermarket compressor for the cabin and adjust the poundage/height from in the cab,.................. or just take the shockers and have the Schroeder valve and lines fitted near the number plate or some place of your liking and pump them up at the servo or have a $ 20.00 mini compressor in the boot.
the spring packs you listed look very expensive to me, if you look in the phone book and find a spring maker that does car and truck springs ,carols, spicers, a 4wd place perhaps, usually they can add a leaf and reset your springs for i would think for much less than the ebay ones, or they could make/supply a helper spring that clips over yours(over load spring).