If you don' t want a 'permanent' stage built with customizing or if you want a stage in a keep or castle you can use this idea that I made for a temporary stage for an event.
It is built with logs as the front, not shown in the picture but at the rear is a stepped log goza stairway. If I get time will build another for a pic later, but it is similar to the front of the stage only starts with 2 logs, 4 logs, 6 logs etc to give the risers and goza to give the treads, the back edge of the building stops you falling off the rear side. The height of the gozas prevents people walking up the front of stage as they block, although you can step off the front if you wish. If you didn't want to be able to step off you can place one of those flat tokuno baskets under the first log in the pile to 'block' the tile from both directions.