shouldnt be any problem with bleaching them in like a 1:10 solution of bleach and water; and you really dont need to soak them, just rub over then rinse thoroughly. depending on how often you use them, since they are silicone, you can even boil them or put them in your dishwasher. if youre worried about the toys you can also use a food-grade sanitizer/bleach which will evaporate on its own.
all gel toys are porous so you wouldnt want to use a chlorine bleach on them (it will make them leach their elasticize faster) so 'sanitary wipes' or 'toy cleaners' are a better idea. Also because the gel toys are porous the bleach can change their color if you dont rinse them completely and dry them.
all in all, you can wash all your toys with simple anti-bacterial soap to get the same effect on both gel and silicone; and it might even be cheaper because you can get giant jugs of anti-bacterial hand soap for like 5$ a bucket.