Custom recoveries have nothing to do with the ROMs installed, meaning you can install them even if there's no ROM installed on your device. Yes, after fully converting to GPe (by running the GPe ROM) you can then boot into the system once then reboot into bootloader and install custom recovery (read online tutorials on how to do it, it's just one or two commands that you enter in fastboot, fairly easy).
I'd recommend using TWRP since it has been wonderful for me even though in the past I used CWM, after booting into TWRP then choosing to reboot it'll automatically tell you that your ROM is not rooted and whether you'd like to root it. If you press install SuperSU it'll install it.