@Remiguel
You are right, GroundTruth is a .NET app which currently runs only on Windows. In the meantime, if you give me your bounding box, I could try generating an IMG file for you with GroundTruth and see if it works properly. I am testing it.

I should definitely check GroundTruth (search for it on the wiki) which has rules tailored for hiking.

You should contact the Italian mailing list. We (Italian OSM mappers) have an agreement with Friuli-Venezia Giulia to import their digital map into OSM. This should help at least with the italian side of the border.

I am not sure access=permissive is right (I'd prefer access=private) however the real problem is that (IMHO) a beach is not a highway, so shouldn't be tagged as such.
I understand that you want it to be routable, but I think that tagging it as highway just for routing is bad. Ideally, routing software should be able to route through areas when access and surface allow.
BTW, if you add access=X, you should also add foot=, etc. because in such cases usually walking is always allowed even if you don't have a permit.
PS: I wouldn't care about a permit-only beach not being routable. If you have a permit, I guess you know if you should route through it. And if you are using a car navigator, it's likely you don't have an appropriate permit.

Bellissimo!
A quando gli altri 4500km? ;)
Io mi sto dando da fare con la rete ciclabile lombarda...
Ciao