Not really gonna have any effect on the rear, and is looking at toe.
If your wheel is sitting exactly vertical to a level surface this would be 0 deg camber as the suspension is lowered or pushed down by weight the suspension will pivot and the top of the wheel move in this would be negative camber. This is moving the contact patch from the center of the tyre towards the inner edge, most vehicle have negative camber to help with cornering but obviously the lower you go the more negative the camber and the more the contact patch moves over the edge of the tyre. Then its going to wear more, much more.
The lower the profile of the tyre the less lateral flex there is in the tyre. The flex in a high profile tyre would allow you to run more negative camber than a low profile tyre. The sportsline runs on 45 profile tyre with a drop of only about 30mm??? you would think that VW have calculated this to not adversely knock the camber out so far when allowing for the max payload of the vehicle.
If you go to a good tyre fitter they will be able to measure your camber and tell you what it is they will also have what it should be.
If you go too low its gonna eat your tyres unless you buy camber adjusters but a low van does look the nuts

and a 30mm drop still allows you to fly a plane between the tyre and the wheel arch.
You may have to live with the tyre wear, you could if the tyres are not directional have them turned around on the rim so the inner edge is now the outer edge. Depends how much a tyre place will charge for this as to whether it would be cost effective mate??