My try of eternal Carthage (career) with max possible LP (10). 10 LP is max because they consume 39.9 grain per year and the available trade route can provide only 40. :(
All city is connected (except of potential land for "cultural park").
Unemployment is 5%-6% stable for decades (probably centuries, I did not check it for so long).
The Census profile stabilized and do not change for decades/centuries (except of small changes (20-30 people) due to specially designed minor devolution/evolution of GI near north farmland). I think this provides additional small "adjustments" of total workforce pool which add something like 20-30 workers in comparison with rock-like stability. Not sure, though, maybe rock like stability is better (just deleting of 2 GI near north farmland shall solve the devolution problem).
Because it is desert province, the eternity is highly connected with prefects behavior which is rather random: for 50, 100, 200 years nothing is burning and then during small periods (5-10 years) fire is occurring here and there (in completely unpredictable and different places). Really no idea how to manage it, perhaps for the road grid I made, there is really no "ideal" prefecture placements (I tried many combinations of them).