[A/S] RV Pad – Sewer Hook-up Question

["Poor Royal" <poor_royal@xxxxxxxxx>]

I'm installing an RV pad for my Airstream along side of my house and 
the guy is here to put the sewer drain in before they pour the 
concrete sometime later this week.  

He is asking me if I want to install a "trap" which would be right 
inside my basement wall, then the pipe would slope down and connect 
to the house sewer-line in the basement about 20ft from the wall.  My 
house sits up high, on a little hill and I am on city sewer.  

I told him that "I" don't think so because wouldn't you want it to be 
as unobstructed as possible?  I'm thinking there is probably traps 
further down-line underground?  

But he is recommending I put one in.  He's here now working on it and 
I sort of need an answer for him quickly, like NOW :)
 
Sorry such short notice but does anyone have an opinion on this?  

Thanks in advance, 
Randy