a darn good option. But I've picked this: (and bought it already before I read your post)
OVAKIA Bumbags Large Capacity Waist Fanny Pack,Men's Sports Fanny Pack Waterproof Waist Bag with Multi-Pockets for Running Hiking Camping Workout Cycling-Black-8 Zipper Pockets : Amazon.co.uk: Sports & Outdoors
www.amazon.co.uk
View attachment 80876 I'm going to cut air holes in the back, and pop rivet in a hard plastic box to keep the air space oepn for the air intake, and secure the blowers plastic stand to the hard plastic with screws. Then the other bag section will house the battery with the power lead linked into the blower compartment. I may even add another filter liner in the bag to filter the air even more (use a vacuum cleaner filter which has a hard plastic shell)
The pipes will come out of two holes on the sides and link up just above the top of the back and be secured with cable ties.