I'm about to change out the chassis batteries in our Allegro. It has Interstate 31-MHD batteries now. They are original to our 2012 model so I'm thinking they were installed in 2011 making them 5 year...
The best "bang for the buck" are flooded cell (wet) golf cart batteries. Yes, they do require maintenance. Checking the water level at least once a month when in use. Less often when in storage.
Applying a generous gob of grease on the posts and terminal will cut down on the fluffy stuff. Cleaning with baking soda and water about once a year is a good idea.
Like any lead acid battery, do not let them fully discharge.