Are you sure you'll be happy with it 3 yrs from now as essentially you are just running loops with very limited switching options and no ability to change direction. Frequently, folks can live without a way to change direction but without switching options grow bored. However, if you enjoy running loops than by all means go for it!
I would suggest changing the design of your bottom siding. Use the curved section of a LH switch as the last curved piece and enter the siding on the straight section of the switch. You'll gain 2 feet in length to the siding and avoid a S-curve.
-Greg