In Australia Cargo Barriers are common place in 4x4s. I have one myself.

Here, these are all safety rated and designed to stop things from the back ending up in the front. There are a standard dealer option for just about every 4x4 on the market, so there are no issues with warranties, insurance or lease payments.

They can be removed and added, normally be removing a series of bolts, but I've never bothered to do that, the barrier lives in the back full time.

Another popular option are draw and shelving systems like Black Widow http://www.bwidow.com.au/ units. (No Affiliation). These meet local collision standards and work really well. They cost, but the quality is very good.

I have a crago barrier, and a I then added a steel shelf horizontally, which is anchored to the chassis. I have a couple of boxes which "lock" under the shelf to prevent them moving, then I put lighter items (clothes, bedding etc) on top.