This altar orientation seems perfect. It is neat and clean. This placement is acceptable according to normal standard. Due to common understanding， idols must be always be lean again a solid wall. An empty wall is enough as supporting mountain.
However, I would always suggest to made a square or rectangular solid wood to strengthen and highlight the back support to the idol. Why? Years of experience tell me so. Many customers after they had done this, good fortune falls on them almost immediately.
Nevertheless, if the height of the idol is taller than 4 feet and put on the ground, you don’t have to make a solid wood back support. A solid wood back support is only applied to those smaller idols which put on the altar as shown in the picture.
There are still many DO & DON’T for altar arrangement.