I did the same thing - made my own, first for 3ph, then put wheels, pump and engine on it. The wheels are on a u-shaped axle so the splitter is up at bench height for normal splitting, can go down to ground level for really big stuff. There are side tables on each side so unsplit pieces have a place to wait. Splitter stays near the finished woodpile.
The really handy aspect is that I can load the FEL with sawed lengths, drive up to the splitter and split everything without bending over ! Pretty cushy !
My vote is for a separate stand-alone splitter. Features to look for are bench-height, 2-stage pump, auto-return valve and roller-guided ram. You'll always enjoy using it - instead of thinking it should be some other way.