horizontal toilet drain

I live in a 3 story townhome with both baths on the upper floor. My wife has hip problems & I would like to put a small bathroom on the main floor. I have a suitable area, but it is above a finished rec room. This rec room already has a boxed in area in the ceiling for heat ducts that i can expand to handle the toilet plumbing. The issue is that to get over to the main sewer in the garage,will entail about a 15 ft horizontal run with possible 2 90's in it before tying into the existing drain. Will this be an issue?

See photos at http://www.vancouver.hm/bath.html

As long as you can get the slope you want, no. That may require a cleanout at one or both of the 90's, though. One of the plumbers will know for sure.

Seems like the waste would not be too much of an issue but the venting will require a bit of tearing up of the floor above to route pipes into the attic to tie into existing vents...
We can run up to 135 degrees of horizontal bend before we need a cleanout in UPC-land...
You don't say where you are so we are at a bit of a loss to help here....

Should be a clean out at every change of direction. MA. State Code