Yes, doing fsl_mc lazyapply on your own dpl blob will work.
To make it ‘permanent’ you can write over the “dpl” partition, like this (from recovery):
mtd erase dpl && mtd write eth-dpl-eth0-only.dtb dtb
The good news is that restool support is now in mainline kernels (since 5.12 IIRC, see this patch)!
You may need to use “legacy” network mode as it appears phylink and dynamically created DPAA2 objects don’t interact too well at the moment.