Transducer install

When I got my sounder I was in a rush to get it installed, and I forgot to sand the plastic before applying the silicon - it eventually gave away on the weekend. I've taken the opportunity to move the transducer from near the foot wells to now have it under the seat area - an area where it is least likely to get knocked by anything put in the front hatch. Is there an area where the transducer should or should not be installed?
Anyway, my main question relates to this. When we have 2 yaks on the car, one travels upside down, meaning that the transducer is hanging from the bottom of the yak. I figure that over time this will lead to stress of the silicon which will eventually fail (especially if it gets hot??). Are there any steps I can take to further secure the transducer so it doesn't matter if it travels upside down?

thanks