Sure you'd be stronger, but for those playing without a backlight you'd also be nearly blind. The GBA SP would spare you from struggling to make out anything on the GBA screen under direct sunlight, but the cartage also went in at the bottom facing you and the floor, not at the top facing the outside world which might have made the sensor less effective.
The original wide GBA, as well as the first run of the SP had a reflective screen, and would look wonderful in direct sunlight. It’s only the second gen of the SP which had a backlight (rather than a front light) and could not perform in the sun.
Oh my. I had a GBA that me and my dad modded to be backlit. Boktai was so good on that system. I didn't think about how lucky I was that I could play the game pretty easily.
