Advice please BX 19 TXD Estate

[Photeauart]

Viewed today. Looking for my first Citroen for a few years as a daily classic. Quite tidy but advice on a few items please. NSR wing very rusty through bubbled paint so will that be hiding worse issues? The offside in the same place had been repaired for crease so of course looked ok. Both bottom rear door shuts starting to show corrosion in the corner… again if I can see it what's likely to be underneath? Sills seem solid apart from a small amount of perforation to underseal along inner sill to floor pan in a couple of places. Looks and feels solid but again should I have concerns that it's tracked out of sight? All floor pan and outriggers seemed clean and solid. A & B posts no visible issues, hinges solid and no movement. Inner wings from inside the engine bay all seem clean and solid. Starts, rises and drives fine. Didn't seem quite a smooth citroen ride in the passenger seat but was ok when I drove it. Not quite wafty! Sphere issues? Thoughts please. 12 months mot just gone on it and at around £900 might be the estate I'm looking for! Many thanks in advance.

[rutter123]

Rear wings on estates do suffer from rust issues usually just below the fuel filler and under the rear bumper, can be repaired but may mean new rear quarter panels worst case. C-pillars rust at base is also quite common depending on how bad the rust is as it can go through to the sills and rear subframe mounts and then you're in a world of pain as this is a big job if not terminal for the car-sadly the demise of a lot of bx's. Also worth checking under the screenwash reservoirs in the bulkhead and under the LHM reservoir and air filter box for rust. Suspension should be soft if not the spheres are going flat but these are fairly easy to change. If its too rusty or in any doubt walk away or you could end up spending another £900 making the car structurally sound. Rust around the rear subframe mounts is a BIG job and usually requires removal of the rear axle and fuel tank.
Other areas to check, boot floor under carpet, exhaust hanger, rear chassis rails, rear corners under bumper, inner sills at the rear end, inside the rear wheel arches front edge/sill, front door hinge plates, top windscreen corners, scuttle panel.