I see this thread is a little old but here is my experience
I have a few guys leased on with me
here is my deal
I furnish trailer,dispatch,fuel card,and trailer repairs.
What they earn this week,they get paid for next week.What fuel they burn
this week comes out of next weeks check.
I get 25% after detention and fuel surcharge is subtracted from the gross.

We use paper logs which are turned in weekly to me along with their bills.

Now about insurance
taking it out weekly can backfire on you.
Say you spring for a guys insurance and want your
money back weekly.He quits leaving you a chunk of
money tied up in insurance.
It is easy to tie up a bunch of money
and things happen leaving you holding the bag.

no way i would do 15%
25 is sometimes not enough.
If someone leases on with you,you take a lot of risks.Every ticket they get goes on you.
Every bad inspection goes on you.For 15 %,I wouldn`t do it.I have done it before for 15% but didn`t make much.
It wasn`t worth it.

a few of the main problems I have came across is

they don`t take good care of the trailers and tires
a tire a week hurts

I used to end up with a lot of money tied up in them and
sometimes it hurt the business when I needed money.Things like insurance
etc

sure these guys I have now make money but it is easily gone.
You have to watch the nickles and dimes every day.

Now the administrative end
it takes time for you to build a drivers file on each driver and
maintain correct paperwork.You will fail big time if you neglect this.
Make sure all paperwork etc is in order in case of a audit.
Any driver who won`t turn in correct paperwork goes out the door unless he corrects his problems