C20W-v5 (the W model is for WISPs) has a similar partition table than C20-v4 (see text below extracted from serial console when device is booting)
Creating 7 MTD partitions on "raspi":
0x000000000000-0x000000020000 : "boot"
0x000000020000-0x000000180000 : "kernel"
0x000000180000-0x0000007c0000 : "rootfs"
mtd: partition "rootfs" set to be root filesystem
0x0000007c0000-0x0000007d0000 : "config"
0x0000007d0000-0x0000007e0000 : "romfile"
0x0000007e0000-0x0000007f0000 : "ispconfig"
0x0000007f0000-0x000000800000 : "radio"
I tried the tp_recovery.bin from C20-v4 by tftp method and it worked !! So C20W-v5 and C20-v4 are compatible.