I usuallly launch single handed.
For that very reason there are places I avoid.
E.g Port Edgar has, on paper all you need - slip, pontoon etc, but it's a *long* walk for a short cut back to the car & trailer, so thankfully as it's a wide slip I can either launch right over to one side to keep the car / trailer out the way as much as possible while I walk / jog back round, or ask someone already afloat to pull the boat over to the pontoon.
I can understand people might not want to trust someone else with their pride & joy, but anyone who has seen the state of my toobs will know why I'm not as bothered letting someone tow/ moor it!
I used to ask people to hold it at the slip, but since I got the hull re-gelled I'm a bit more protective of the underside!
But yeah, in summary there are places I just wouldn't bother launching single handed, even if it means going somewhere with a bigger launch fee - the hassle reduction is worth the money!
Also setting up the trailer well can improve slip timing a lot.