RE: Scale olde non-lead sled
Sorry your scale idea got a little side tracked. Didn't think that the free flight design was going to fit your request but it's still going to be a fun project.
Now back to your request on a pre WW2 scale sailplane that is hi-startable. As there is very little demand for this type of RC sailplane or you would see significant production. Instead we see slope monsters that are predominate in Europe. True there are about twenty scale die hards here in the states but even these do mostly aero tows as trying to winch a 1/4 and even 1/2 scale monster is tenuous at best.
In a way I take a bit of offence at your reference to garage manufacturers. There is not a great deal of profit in specialized RC sailplane manufacturing. Even Sal at North East has collected most of his products from small one or two man shops that could not make it alone.
About the only way to do a 100 to 120 inch stand off scale high startable RC sailplane is to do it yourself. Or find someone that has plans that you can build from. Either way it is still an engineering project.