The reason I asked is that there are double racks for the rocket pod/fuel tank combo, though they are over-wing on the Lightning. Still, looking at single rocket pod/fuel tank combos on the outboard pylons of French Phantoms with a twin-DEFA gun fit replacing the M61 in the nose and ATAR 9K's replacing the J79's.
The Lightning overwing load used a custom adaptor, not a TER though. The setup on the phantom was 'show only' so I suspect they were just regular rocket pods.
Note that the JL-100 combined fuel/rocket pod used 68mm SNEB rockets with two rings of tubes, while the pods in the F-4K pic are Microcell 2" (51mm) pods with three rings of tubes. I've never seen a JL-100 variant with 51mm tubes, nor would I expect to since they're a French store and the 2" RPs are British. Having said that, I see no reason in principle why a JL-100-style pod couldn't be made up with 2" tubes. I think the diameters of the two pods are pretty similar.
BTW, the reason that the RN used the 2" RPs while the RAF went to 68mm SNEBs was that the latter wern't sufficiently hardened against RFI problems for the shipboard environment. When RAF Harriers went to the Falklands, they had to be quickly cleared to fire Navy 2" RPs for that reason.
Another solution to the gun 'problem' with British/French Phantoms would be to adopt the Vulcan II cannon developed just after the 20mm Vulcan but never put into production. This used the ADEN/DEFA 30x113mm ammo and was roughly the same size as the 20mm weapon. Since the US had no interest in it, you could probably licence-produce it in the UK and/or France.
If the French Phantoms were to be used from their carriers, then ATAR-9Ks would be a very poor choice since their thrust and thrust/weight ratio were significantly worse than the J-79. If anything, they'd probably have to adopt the UK Spey fit for the same reasons: safe take-off from weaker catapults than the US ones and faster response to a throttle slam in the event of a go-around.