1/2 inch per foot is way too much slope for a patio regardless of what
you use to install it and it's going to have an obvious slope. If you
try to put a 5 ft table on it, one end is going to be 2 1/2 inchs lower
than the other and it's going to be obvious something is very wrong.
A slope of 1/8 to 1/4" per foot is typical. If you go with 3/16, that
cuts your delta at the far end down to 3 inchs. Then I would either
use a 3 ft wide planting bed for shrubs, flowers, etc for the
transition, or else change the grade of the existing grass over the
next 5 ft of so by renting a sod cutter and adding topsoil. If you
go with the planting bed idea, you can use a couple large stepping
stones in the bed spots you want to use as walkways.