I browsed that thread a little more, that was for a 48" wing and should work for you.
If you want to try a different wing, I would recommend a Kline-Fogelman airfoil wing with polyhedral tips. That would look something like this:
The tips could be short, about 8" long and would only need about 2" of dihedral or rise at the tips. The advantage of that wing, if you made it 48" wide, would be that you would have a flat 32" center section and that is much easier to build and much stronger than having a dihedral joint in the center of the wing.
Look at the way this wing is built, that is what I am recommending for your wing:
Blu Baby 33" KFm3P Polyhedral Tip Wing Build - http://www.rcgroups.com/forums/showthread.php?t=1474665
You can leave the 75% step off on that and it will be a KFm2 wing and a little lighter. It is easy to add spar to the center 32" section and the tips will be strong enough if you use the tape wrap and PU glue joint as I did there.
That is a slow flying and stable wing, it would be good for a trainer as long as you use your head a little and do a test glide to get the CG right and don't try to fly at full throttle from the start. Start of easy and it will go fine.
Here you can see a KFm2 wing with polyhedral tips on its first flight on a full sized (48" wing) Slow Stick clone. That plane had plenty of power, the pilots are experienced, but a newbie could fly that plane too. This was the first ever flight of this type of wing on that plane:
The details on the build on that wing is here: