Can't give an answer on any de-confliction service, but doubt it would be a problem to track the a/c near the foothills of the Pyrenees, unless they were very low. For example, there's an enclosed radar transceiver in a tower on a hill near Pujaudran - about 15 miles due west of Blagnac. From up there (close to the main, N128 road from Toulouse to Auch), a long section of the Pyrenean chain is visible - from south-east to south-west - on a clear day.
BTW, surely an east-west racetrack based on Blagnac would not go anywhere near the Pyrenees? There seems to be a military low-level route from Toulouse-Francazal that tracks a bit south of west. It is used by Transalls and Hercs going to a parachuting zone in the region of Pau. But since the Paras moved out of Francazal, the daily commute has ceased. Perhaps they are mainly in Africa...