The Neolithic side of Tara is an odd one. Of all the monuments on the Hill today, only one is that old - The Mound of Hostages. In passage tomb terms it's a tiddler, totally overshadowed by the nearby Boyne Valley sites. 50 miles to the south the much more impressive and important sites in the Wicklow Mountains dominate.

Just north of this around the highest point there is a massive rock-cut henge which was 150m or so in diameter and lined with massive wooden posts. There were other megalithic monuments still on the hill aound 800ce. A couple of stone circles, maybe a tomb or two and some standing stones. Now they are gone we can never know their age, but the variety of types does point at long term, possibly uninterupted use for quite some time.

To answer your question no camps have ever been found. There are two massive hillforts nearby, which haven't been properly tested, that could have been used. The plain to the west has been extensively surveyed by the Tara Project and little was found that would indicate such sites. Obviously, this doesn't mean they aren't there.

There were five roads that met at Tara. These came from the 5 kingdoms and I reckon they were very old routes indeed. The N3 runs along one of these. If there are any camps then they would be along these routes.

The main thing is that Tara probably wasn't all that important in the Neolithic. Just look at what's around it! You have the Boyne Valley for a start. Then you have Teltown, probably one of the most important sites in Europe, that was still in use up to the early 1800s. Tara probably had a brief Neolithic era. The henge was out of use when the Mound of the Hostages was built then you have nothing for a couple of thousand years that can be confirmed.