Hi,
Using any of Auctiva's ready made templates, you can choose picture Grouping:Vertical and Alignment:Left to achieve that organization. That's done when you select the Template on the one-page listing editor.
Some of Auctiva's templates would probably work better than others due to page-width, margins, border, etc. for that arrangement.
Try that. If it's not exactly what you want, a custom template is needed.
Danno