May or may not fit your exact requirements, but Freestyle's APHS, which is primarily designed as a graphic arts film, may work. Abundant in various sizes, and is very inexpensive. Development under a red safelight is also built in. There are many posts here about how to process APHS in different developers for different applications, including in-camera shooting. My estimated EI for APHS in bright daylight is about ISO 4 or thereabouts.