Anything cage and bag would work fine for those who don't / can't DIY MYOG
i bought one of the new Salsa anything cage HDs and a Salsa anything bag to go with it thinking i would run it under the down tube.
given its fairly large diameter the anything bag does not clear my chainrings/chain in either water bottle boss position on my size XXL santa cruz TallboyC. it does clear on my borealis echo due to the wider bottom bracket shell but after mounting it and looking at the clearances i am not sure i want to go that route and will probably just send the cage and bag back. YMMV