Management fee structures when the owner wants 8 percent flat

I run management for a handful of scattered SFR owners and one of them just pushed back hard on my fee schedule. He wants 8 percent flat, no leasing fee, no renewal fee, no markup on maintenance coordination. His argument is that the ATTOM style yield compression means his numbers don't work at 10 percent plus a full month leasing commission, and he's not wrong about his numbers, his gross is $2,150 on a house that cost him $340,000.

What I'm stuck on is whether the 8 percent flat model is actually survivable on scattered single family. My cost per door on turns is what kills me. A vacancy on a detached house with a yard means landscaping, a full paint, and three or four trips that a stacked duplex wouldn't need. Leasing fee is where I recover that labor.

Has anyone here priced a genuinely flat-fee scattered SFR book and made it work at scale, or does it only work if you're also taking the maintenance margin? And if you moved an owner from percentage-plus-leasing to flat, did the relationship get better or did it just move the argument to which repairs get approved?