I don't know of any way around doing the constraints...would be nice. As would a simple "offset" in the sketch workbench. While it's true that you don't absolutely "need" to fully constrain "simple" sketches, it's a good habit to get into and will save you grief on projects that are slightly more complex. As an example...prototyping a 1911 grip frame for 22xx. Was a nightmare to get the filleting to work until I started over with fully constrained sketches. Will eventually be a cast/machined part.
I usually use a multi-line to get the rough shape and then go around and constrain the elements. It looks strange when you add the first constraints but then it straightens out. You can also use a spreadsheet to constrain all off the elements.
I wish I had learned AutoCAD years ago, but I could never afford it.... Now that they have gone to a subscription based service (instead of buying it) I'm glad I didn't, as I sure dislike the monthly fee model, especially at today's price.... It's great if you have a business paying for it, for hobby use, not so much!....Bob