You're really going up to a good size on this one. When I build planes over 40", I end up smacking all the models hanging in the build room above the table.
Building up to 53", I've been able to use the same methods and thin sheeting that I use on smaller planes, but at 84" it would probably take some rethinking, as well as not being able to predict the AUW and choose the power system off top of head. Looks like a good project.