I have a long wire shortwave antenna for receiving shortwave. It's just
a piece of insulated wire between the house and a tree, about 35ft long.
I have a shortwave radio in my bedroom connected to it.

But I also have a work shop in my house, which is on the other end of
the house, about 40ft away. I work on a lot of radios in my shop, mostly
old tube type SW radios. I want to run that same antenna to that shop,
but I'm doubling the length of it, and that extra wire would be run on
the outside of a metal sided building, on insulators. (I'd rather not
have to run it thru the whole house, exposed on the inside, or try to
fish it thru the tight crawl space under the house).

I was told that the length of the long wire is not all that critical,
but this will make a huge difference in length, and I am a bit concerned
about running it along side of the metal house for 40ft.

Will this work?

If there was another tree nearby, I'd just run another wire and have two
antennas, but there is no tree, and putting in a post is too much work
and expense.

What is the best way to accomplish this, so I have an antenna is both
parts of the house?