if you need an external drive try a 2.5" SSD in a usb caddy. With no moving parts it should hold up better than a mechanical drive in higher temps where the grease in the engine will cook and cause drive failure. Downside is the ssd will be thrashed with constant writes, but thats no different than the SD card. SSD have much lower power requirements and can be powered from the pi only. Bigger drive should last longer.
Im told a lot of SD card failures in pis are caused by insufficient power in the pis. While I cant say much about this my orchid pi is running off a 12v UPS designed for CCD with an ebay buck converter 12v->5v. The voltage converter has press buttons to set the voltage and shows you current and I run the pi at 5.1v just to give it that little bit extra to account for voltage drop in the supply cable. A mate of mine swears the power is the reason for SSD failures and does similar. His has been solid too. Other people have problem SD after problem SD which makes me think it probably is not the SD card thats the root cause. Make what you will of this, its a small sample size and unconfirmed.