I would love to do this to my toy hauler also. I have a pull down screen between the garage and the ramp/patio (factory patio option). Mine did not come with any option to put a "three season" door or wall between the garage and ramp/patio and I would really like one. I've looked at the construction of them at various RV shows and they don't look all that hard to build. I'm seriously considering just trying to build it myself. Only thing holding my back is I'm not sure which end of the screw driver I'm supposed to be holding onto when cutting wood
for the frame . . .