Yes, they will. And just a fyi the border fence varies between 18 and 27 feet, not 30 ft.
I'd propose various other methods of stopping the flow of illegals into this country that would be more effective. For starters, I'd invest in more high tech surveillance. Personally I think that is money better spent. I'd also work with Mexico to protect their southern border (it's only 541 miles wide). I'd also work with the countries where the illegals are coming from to make things better so people wouldnt have to trek 1,000+ miles just to survive (to me this is the most important). I'd also beef up port of entry security. Just some thoughts off the top of my head.
But soon enough we're going to experience the Asian wave of illegals as they overtake Latino's as the main illegal entering the country. Because that is what is going to happen. Pretty sure we cant build a wall around the entire country.