Rear discharge Toilet help

[jikoch]

I have a cleanout 11" off the basement floor in a finished basement wall. This main is coming straight down from a bathroom directly above on the first floor.
Id like to place a rear discharge toilet up against that main line in the basement ( where the cleanout is located ) and run a rear discharge toilet into that main.

Does this seem like an acceptable option for me? Any concerns?
Your help is greatly appreciated.

[Terry]

Whenever the upstairs toilet is flushed, it's going to burp air into the downstairs bowl, and you will lose water in the bowl. Flush the upper one a few times, and you won't have any water in the lower toilet bowl.

If you intend to add a toilet below the upstairs plumbing, it will need to be vented "before" it enters the waste stack.