There isn't really a shortcut, no. There are often ways to reuse some tiles for multiple positions, but unless your wall is visually designed to be built out of boxes, there's no getting around having numerous tiles for different arrangements. It doesn't have to be a very high number of them though, and most tile editors support automatically determining which tiles to use based on context.
As for the hole - the usual "solution" to this is to not place the tiles that way xP If there isn't a visible floor, players will often not think to go there, so you generally want to have the floor visible by making the hallways wide enough.
You could make the wall tops narrower (thinner walls), but this would require more variant tiles, since
An alternative solution is not to use two tiles per wall segment, but one tile that contains both visible sides of the wall (it'd be a thinner wall). That way the walls do not block any walkable areas, so things are never confusing. The downside, of course, is then the characters can never appear behind walls, which can look unnatural with larger tile sizes like this.
Edit: Your mock-up is missing tiles for walls placed in arrangements of 3x3 (to cover wall segments that are thicker than a tile, e.g. 2x2, 2x3, 4x356, whatever). Unless you have a way to prevent these arrangements, you may want to include those.