Running Pex in craw space

Hi all,
I am thinking of running a Home Run PEX system in my beach house. All I have is 1 and a 1/2 bath, clothes washer and kitchen sink plus I think I am going to add two hose bibs. I am going to run a manifold in the closet where the hot water heater is and run individual lines to each fixture with shut offs at the manifold. I guess my biggest question is, I live in Delaware and we get pretty cold winters here. My house is on a 5 block high crawl space with vents and was wondering if I would be taking a chance on pipes freezing in the winter. I am not there much in the winter and the heat is mostly set at around 50-55 degree's in the house when not there. I know that with Pex and a home run set up I can not keep the piping up in between the floor joist with the insulation. I have seen other houses on crawl spaces that have CPVC plumbing and from what I can find out they have not had any frozen pipes and they are exposed. Do you think the temps would be warm enough in the craw space to keep the PEX from freezing? I know it can take some freezing but I want to try to eliminate that from happening. Also what is you take on putting in copper stub outs at each fixture. The stub outs would have a crimp inside the wall. Any info would be appreciated.

Thanks,
Ron

I take it the house is all ready built. It would have been best to run it all in the walls.

Would it be possible to run each of the PEX runs under the crawl space with a downward slope? You could put in a T and a valve on the bottom to drain out the water. This would increase the price the price but it might be cheaper to use 1 hot and 1 cold run to each part of the house. There would be a few details to work out if you did this.

When you would go to leave you could open the valves and open the facets and get a good amount of water out of the system. When you return close it all off and open the water back up to the system.

With copper it would burst. PVC would crack. But PEX would be the best bet for this install.