Personally I just use a mug that fills up with water from the water bath and put it on top of the bag(s) for some additional weight.
Although, I feel somewhat compelled to ask, why are your bags floating in the first place? Aside from vegetables, which are notorious for floating, most other food should be dense enough to sink, or at least not break over the water level. Could there be an issue with your vacuum sealing technique? I heard it’s sometimes good to shift the food around in the bag during sealing, so that all of the air is evacuated. Personally, I’ve used the water displacement + manual sucking method on several occasions, and my steaks were able to stay completely immersed even then.