Bill, K6TAJ wrote:
"Thinking about getting through walls with ladder line."

I`ve brought open wire lines through walls by Pyrex bowl insulators
mounted on a sheet of plywood framed into the wall as if it were a
window. The plywood between the conductors seemed not to hurt. Glass or
Plexiglas would be better and might obviate the bowl insulators.

You also could cut the plywood, Plexiglas, or glass sheet to fit under a
window sash. Then, just lower the sash on the sheet.

You want innocuous materials between the wires and surrounding the line
by at least several times the spacing between the wires.

Best regards, Richard Harrison, KB5WZI