Many years ago I needed a big dovetail cutter - not that big, but chunky.
I started with a nice piece of steel, welded it to a 40 taper shank then turned it to the 60 deg angle I wanted. Then off to the mill with an indexing head and 3 slots cut in it with the leading face on the centre line. Welded in 3 sticks of HSS and off to the T&C grinder to clean it up.
Worked fine, it's still floating about somewhere. I can't see why a bigger/heavier version wouldn't work and if it needs carbide, so what, braze them in (welding worked but there was some cracking, I just didn't care for a one-off and it was quicker). I'd probably TIG braze them nowadays.
Or just use the planer which would likely be my pick as long as you can set a stop so you don't need to baby-sit it. Slew the slide over, engage the power feed & go do something else until it stops.
PDW