That is true of the older style converters, but modern electronic switch mode converters do not exhibit AC or DC 'ripple effect' problems. IOTA specifies that their units can be operated without batteries, and I have installed several in units where the battery was bad and not replaced. These units are tied to concrete pads and do not move, so the presence of a battery is not required. No problems have been noticed with any of their DC components for several years.
OTOH, any trailer that is taken on the road MUST have a battery installed to operate the break-a-way safety switch in the trailer's braking system.
Solar Tech Energy Systems, Inc.
Victron Solar Components and Inverters, Zamp Solar Panels, LiFeBlue and Battle Born Lithium Batteries, Lifeline AGM Batteries