If you can hold the weight down to 130g, your 50 watts of motor may actually do the job nicely. The rule of thumb for large planes seems to be 7W per ounce on average, 11W per ounce peak. For smaller planes it's more like 10W per ounce average, and I haven't a clue of the peak value needed (more than 11, probably).
Here's my Beginner Ringmaster on the scale (that plywood is not part of the weight you see -- the number on the scale is all plane). In addition, I've got a Beginner-Ringmaster-Like-Thing for comparison -- it's got less wood and no landing gear, which is probably where the 20 missing grams went.
Finish on both of these planes is a few coats of clear dope, then tissue, with colored tissue (and decals, in the case of the Beginner Ringmaster) for trim. It's light, and it looks pretty good. Hinges are sewn on after finishing (I always finish first and then hinge).
Both of these are promising fliers, but with problems that keep them hanging on the wall -- the Cox one won't stay running inverted, and the Wen-Mac one won't keep line tension inverted. But for flying level in a circle and then falling down from dizziness, they're great.