A direct vent stove will definitely be the best choice for your application, due to the close clearances they offer and the ability to be horizontally vented. The stoves are able to be cornered, as you mentioned and can be vented horizontally through the wall. A termination would be placed directly on the outside wall, with no rise required. The stove will draw fresh air from the outdoors for combustion, so room air is not negatively affected.
One popular stove that we carry for tight applications and lower heat output is the Napoleon Arlington Direct Vent Cast Iron Gas Stove
. This unit measures 26 3/8 inches tall, 19 1/4 inches wide, and 15 3/4 inches deep. It also only requires 2 inches of clearance from the corner of the stove to a wall. I invite you to review the video on the item page for more information.