Well I would suggest either a double barrel rail with i believe 1.5 inch diameter pipes or a 4 pipe rail with 1/2 inch pipes. You shouldn't have a problem with pipe cracking unless you are coming down from a high spot onto the rail. I have had some cracking a few times but that is because of excessive use 270 ing on. Now for ware and tear. I think after excessive use you may see white ish marks on the bottom of your skis but that is after 100s of times hitting it. The most wear and tear you will get will be during the summer if you are landing on rocks or anything but astroturf. If you are using grass you will be fine i think. I personally use 4 pipe rails on a 2x4 and it works great. You can look at some of my videos if you wish.
Here is my most recent edit