This is a bad idea. By definition, the thieves have metal cutting devices with them. You can still access from front or rear. Putting the split in the center makes it trivial to lean back on the fence and the two pieces will swing open like gates. Maybe, if you're lucky, they thieves are extra dumb or lazy and pick your neighbour instead but if they have half a brain, this is nothing. It also takes time and effort to setup every time you park. A far better implementation would a similar idea left permanently in your driveway (the most likely place to get hit). That can block three sides and can not be pulled apart by hand as the sides are not collapsible. You still have the problems of one open side and thieves with metal cutting devices. The open side could be dealt with by a locking swing gate (almost 100% change you will drive into it and crush it though given enough time).
If you want to do something, the best I have seen so far is a heat resistant wire over the top of the cat. Not really visible from below and wire gets cut when they cut the pipes. Cutting that wire connects a car horn (easiest would be dropping a relay but there are other ways to accomplish the task). That both draws a lot of attention and makes it a very unpleasant place to continue working. You still need a repair but probably didn't lose any pieces. Some downsides are upfront cost and it's not trivial to avoid power drain from this type of system. On a vehicle driven daily, power is probably not an issue. If I drove a truck and parked outside at night, I might consider something. I try to drive lower vehicles that make access annoying (not too many thieves bring a jack on their exploits).