Very nice build, I nearly fell into the same trap wanting to build a RAF Wessex with a hump. XT257 was a development aircraft and was never in front line service, I think she ended up being an instructional airframe and got her yellow coat and markings during that period, eventually ending up in Bourmouth, So you can actually just display her as normal after weathering.
http://www.planesandchoppers.com/picture/number14892.asp
Happy Modeling
John