With flooded lead acid battery you can do partial state of charge (PSOC) for a week or so and then bring them back to almost(?) full capacity with a long dose of high equalization voltage. In the past, we've done this without obvious problems. It no doubt reduces their lifespan but you gotta do what you gotta do.
Some lead acid batteries last longer under PSOC conditions than others, usually those with "carbon" supplements like Trojan's SmartCarbon in the T105RE and their Premium and Industrial lines. Or Outback's Nanocarbon AGMs.