adobe photoshop - Creating large banners to be viewed from a distance, at a size Illustrator can't handle

I need to design large banner, 40ft X 10ft, but Illustrator can't handle that size, so I create it at 1/3 size in Illustrator. Once done, I export a web image (JPEG), and set it to 100% quality. Then using Photoshop, I create a 40ft X 10ft size canvas but lower the resolution to 60 to create a pdf file.

Basically, I resize the JPEG to its real size using photoshop and save as pdf for printing.

The banner will be seen by anyone from 80 meters, something like that..

1. In Illustrator, the canvas size is 1/3 from 40ft X 10ft


2. Once I done my design, I saved it as web image, set it 100% quality


3. Then, I create real size in Photoshop (40ft X 10ft) but lowered the resolution to 60ppi



4. The image that I saved from Illustrator will be resized to its real size in Photoshop, and save as .PDF.

Is this the correct process?