It's not just about depth of discharge. You should also bring them to 95-99% on most days.
With solar you might still have to run a generator if solar alone can't bring batts to over 90% for more than a few days. Then you run a genny for an hour and let solar complete the charge. On weekend trips I wouldn't worry about charging them full 99% if it stays on shore charger with 14V hump rest of the week.
Shallow cycling under 5% - led acid battery is not AA NiCd, they have no memory effect. There is "some" evidence of damaging effects of shallow cycling in wet batteries, but it seems that frequent discharging below 50% kills them much faster.
