I can't have sugar substitutes and I don't care for stevia at all. I followed the vegetarian diet plan over on the official SBD site for a while substituting meat/poultry/fish for the tofu (can't have soy either). Those menus did not use ANY sugar substitutes but rather relied on the sugars and sweetness of fruits as in LF ricotta with pear or cantelope. I put fruit in my oatmeal (chopped apples, organic unsw. applesauce, banana, blueberries, etc.). Something to try when you get into PH2. On PH1 I did not have any of the suggested sweet things.
Other PH2 stuff: I DO use 1 tsp of honey or maple syrup on occasion & count it towards my sweet treat. I also use raw sugar/honey/maple syrup/molasses when baking bread. The amount I use is substantially less than commercial breads use plus no preservatives/chemicals.
This brings up a point to consider regarding sugars. Commercially prepared products contain a lot more sugar & salt than what you make yourself. Using them and then using sugar substitutes may seem on plan but is it really?
I think one of the major points of the SBD is to eat a healthier more natural diet. If you are used to a lot of sweet things in your eating it may take a little time but your tastes will change to appreciate the natural sweetness in foods (esp. fruit). You can easily follow SB without sweeteners.