Don't think that bit of fencing will stop them. 
If they move stuff to get on common land, it becomes trespass, and the ol' bill can move them on straight away. If they don't, you have to go through a 3 week legal process to move the scum on. Same applies to footpaths etc
That's why you are currently getting farmers parking scrap cars across all the gateways.
I know a lass who works for an adjoining County Council, in Gypsy Services. This whole department is not about assisting the pikeys, but moving the lazy, disgusting, thieving pikeys on. So even more tax payers money. Great.
Unless one of them is pregnant or has health issues, in which case they can't move them regardless of who's land they are on. the wooden fences won't do a thing, they'll claim it was already broken.
We had the same situation at the park behind us a couple of years ago, was a nightmare and cost us - the council tax payer to get the place cleaned up.... aparently smearing dogshit all over the childrens play area is acceptable as we have to understand that they can't help their behaviour.
Anyway, what seems to keep them out is big ditches and mounds.