Scenario:  1/2 sheet cake for two boys graduating from two different schools.

Invitation to their joint party has a photo of them with their backs against a train trestle.

I've sculpted the boys already and they are approximately 7" high.

I need suggestions on how to sculpt/mold/erect a trestle for them each to lean against.  

For once, Google has not been helpful so I'm turning to you, the Cake Experts here for help.

Thanks,

Martie