I believe as a person who stutters and stutters so severely that it makes Porky Pig sound fluent, that word substitutions is 100% okay. My position is do what ever trick you have to do. Some SLPs say you should stutter through your blocks. I always attempt to plan out what I am going to say so that I will not stutter in front of the person I am speaking to won’t think I am bat shit crazy. We as people who stutter are in constant 24 hours a day, 7 days a week, 365 days a year surviving mode. OP, I applaud you for what you are doing with the methods you are doing to over come your stuttering even for a brief moment in time.