Large Banner is huge in size Photoshop

Hello,

I am working on a large banner used for a photobooth background. The banner would measure out to 160 in (approx 13.5 ft) X 90 in (Approx 7.5 ft). When working on photoshop and inputting those dimensions at 300 DPI in photoshop, the file size is 8.5GB (which is absolutely ridiculous). However, I am not too sure what DPI or size I should work in photoshop inorder to reduce the files sizes. I managed to export the image to a JPEG (336MB) with the same specs and I placed it in InDesign. When I export the file to a PDF it comes out to 1.28GB??? Can someone please explain to me the proper methods when designing and export for super large print format?

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