I tend to split my photos by month/year so if you’re not doing that it will help.
Well that is exactly what he/she don’t want to do.
You can try to connect an external HDD (instead of SD card), especially if you buy a Banana pi. Since Banana Pi BPI-M1 has a SATA connector.
Maybe it’s possible to turn off thumbnails or better… it is possible to schedule them via cronjob (if not already done?).
Ow… did you put your Pi in a box or something? Place it is a good ventilated space NO plastic case!
EDIT: You can also choose for the Banana Pi BPI-M2U, which is even stronger.
Futhermore, there is an article about it:
Be aware that you need to cool 2 parts (chips) on the PCB that can get really hot (not only the CPU).