Apple has never kept anyone from doing any sort of repair on their own computers. All they can do is to threaten to void the remaining warranty.
I am a competent technician. When my Macs are out of warranty, I do my own repairs/mods. You claim to be competent: do the same.
Hmmm, what company tends to void the warranty when you change a battery? Hmmmm, let me guess Apple, because no other company is stupid enough to pull that crap on their customers.