My wife and I have just returned from a week of hiking in and near the eastern Pyrenees, starting from Foix, having flown in to Toulouse.
From there we did three days on the Sentier Cathar, which follows the route of the GR107, then a day south on the GR107 to Ax les Thermes, where we spent a very pleasant day. Then we spent three days on the Carlit Massif, first along the GR10 from Merens les Vals, followed by a final day back to the end of the French train line at Entveigt / Latour les Carols, via a stretch of the Route due Carlit. It is a very lovely area, with lots of options for making up a tour of about a week.
We had more guides than we needed (because I can't resist buying them, in English or French) but you could easily find your way without them, if weight was critical, using just the 1:50000 map for the area. The routes are well marked with red and white markers for the GR routes, and red and yellow for the others that we used. The guides do give you an idea of how much ascent/descent you are in for, however, and how long the day's walking is likely to take. We always took longer than the suggested times, however. We normally set out by 7:30-8:00 in order to get some distance behind us before the heat of the afternoon.
The only places where it was remotely crowded were where we approached civilisation, for example at the Lac Bioullouse. Otherwise it was gloriously empty, and we actually liked to meet our few fellow travellers along the way when we bumped into them.
At Montsegur we camped at a beautiful, simple, quiet and cheap (4 euros each!) municipal camp site.
We had a tent and slept in it most nights, but mostly outside refuges when in the mountains, and at campsites or gites when lower down. Even lower down, on the Sentier Cathar, you have to think ahead as to whether there will be shops where you can buy food. In the mountains it was significantly cooler than low down, though still felt warm, and we managed OK for water by using fountains at villages when we came across them.
There were plenty of opportunities for wild camping, but I didn't see anyone doing it, probably because the proximity to refuges where we were meant that it wasn't necessary. In fact, unless you are completely averse to using refuges, or are going to an area where they are not where you want them to be, you might want to consider ditching the tent and just using the refuges. I think we saved 18ish euros a night each by using our tent, but had the weight penalty instead.
All the hikers we saw who were doing the whole stretch from Hendaye to Banyuls, or vice-versa, by whichever route, did have tents with them.
I would have loved to see a bear, but the closest I came was a marmot.
We both very much want to go back and do more.