A long time ago in a galaxy far, far, away....
The MoCo used to provide true dual exhaust on iron head Sporty's.... So their around the front concept is one option for routing the pipes (Ness liked to do this with Digger Sportys back in "the day").
Here are the OEM pipes are separated from the bike
Here is another Concept
There are lots of Custom exhaust shops out there that can fix something like these up for you
Here are what the pieces look like
and one more...
The crossover pipe was made by putting a U shaped dip in the pipe to get it, and the heat, away from the belt.
The pipe comes out on the other side as close to the case as possible to make it appear it came from under the bike
The rear muffler support bracket mount on the frame is used to mount the pipe.
A support arm is welded to the right pipe. The left pipe is pretty solid with stock attachment schemes but one is added for peace of mind
I L.O.V.E. love customizing trikes....
Here is the exhaust for my latest science project.... It was born of an idea, then a sketch, then some tube and a mig welder....
Now they are on my engine....
To quote the famous Boston rock poet Steven Tyler.... Dream On!!
Good luck with your project!