The only answer is "maybe". Wifi range and quality in RV parks vary tremendously, from park to park and also your location in the park. Few parks have good wifi reception on every site, and even if you have a good signal you may encounter poor performance due to overloading, i.e. to little internet bandwidth for too many users. Jeff's recommendation for a top quality wifi receiver such as the Super USB Wifi (I have one of those myself) will go a long way toward getting you a decent signal, but its impossible to say if that will be sufficient for you in your campground and site. Your own usage is another factor - if you are expecting to stream video, the answer is probably No, but if you mostly read email and occasional light web surfing, you can probably get by even if overall performance is poor.
Are you even sure the campground has wifi at the sites? Many parks have learned to advertise wifi availability only near the office or rec-room becasue other parts of the campground simply don't cut it. You should have a heart to heart discussion with the campground management about that.