hello @Chridster1,
thanks for the update, i'll discuss with team in terms of meta-layer releases; for the build issue, please try prebuilt gcc and see if it works:
$ make ARCH=arm64 CROSS_COMPILE=../prebuilts/gcc/linux-x86/aarch64/gcc-linaro-6.3.1-2017.05-x86_64_aarch64-linux-gnu/bin/aarch64-linux-gnu- tinker_board_2_defconfig
$ make ARCH=arm64 CROSS_COMPILE=../prebuilts/gcc/linux-x86/aarch64/gcc-linaro-6.3.1-2017.05-x86_64_aarch64-linux-gnu/bin/aarch64-linux-gnu- rk3399-tinker_board_2.img -j8