I like marking pens, but you can use your favorite method to mark where a design goes.
Use a topper on the front and either wash-away, tear-away, or cut-away on the back.
You can hoop your towel or secure it outside the hoop if it is too thick.
Load the hoop in machine, set design, and check needle and thread.
Press start and watch it go!
Remove stabilizers and trim threads. Remove markings, too.