Perhaps there is no Basingstoke to Waterloo route which would explain a lack of responses. One alternative which wouldn't require any great route buildiing skills is to alter a route you like by making simple changes such as station names and so on. While it might not be prototypical, at least it's a compromise of sorts and will give you something to run on until someone does (maybe) produce the route you really want. Unfortunately, I don't have any suggestions myself as I've only ever downloaded the Midshire Mainline route which is OHLE.
When you're awaiting replies, give it a few days as not everyone checks on the forums every day. It could be that someone has the answer but only comes online at weekends. Bumping threads after 4 hours is likely to have the reverse effect that you desire. 70 views and no replies is quite normal when you consider the demographic of Trainz users.