I'd suggest digging into the exact dollar amounts on a monthly and annual basis rather that measuring by rate percentages.

I've been told the hard part is finding a builder who's willing to build without me paying a large percentage upfront.

The only thing that’s consistent is that a HUGE percentage of people (99%?)

It’s total BS, or, it’s random luck of a very small percentage, like winning a lottery.4.

Is that amount a percentage of the sales price ?   

Should be based on percentage share of partnership, but is ultimately the GPs call.

I've been told the hard part is finding a builder who's willing to build without me paying a large percentage upfront.

What is your vacancy rate percentage when calculating monthly income?

I would never agree to include their chosen payment percentage in the lease. 

I am in the process of taking on clients for co-hosting in addition to continuing to self-manage my own portfolio want to get a feel for what folks are charging their clients.I've spoken to a few folks already that manage between 15-30 and I've received feedback that they charge anywhere from 20-30%.For context, I've already decided to charge a percentage of Gross Booking Revenue excluding Cleaning Fee.