The 1.250 SG when batts are "full" is what I was seeing on my "learner" first pair of 6s. This was before I learned they needed 15v etc. That sulfation was permanent by then, and their AH capacity was reduced from original rating. ISTR about 3/4 sort of goes with 1.250/12.5v SOC idea. Don't know if that is a coincidence or if it comes out the same for aging batts too.
Anyway, Salvo can get more use from them as long as the AH capacity they now have is still enough for his usage. With solar "hiding" what the batteries are "really like" that could go on for quite some time.
Mine didn't last much longer after that since I was working them hard at 50-90s no solar. Got too low in capacity and were tossed, but they were still working.
IMO it might be worth a serious "recovery" effort to get that 1.250 up to maybe 1.260. Not likely to get better than that, but could happen.
New batteries next year? Maybe. Probably. But as Salvo says, they won't break the bank, and four-five years is not bad for that approach to battery/RV operation.