Water Line Freeze Prevention

I am running a pex water supply line from my main house to a small outbuilding about 40ft away where I'd like to have a bathroom.

Unfortunately due to rock ledge, I can only get the line about 36" deep. This is in southern CT where the freeze line is apparently around 48"????

Will it be ok, or should I run a heat cable like this along the line?

https://www.briskheat.com/products/speedtrace-extreme-self-regulating-heating-cable?variant=47614458134668&country=US&currency=USD&utm\_medium=product\_sync&utm\_source=google&utm\_content=sag\_organic&utm\_campaign=sag\_organic&gad\_source=1&gad\_campaignid=24125689620&gbraid=0AAAAAD5Y\_ssjpDOs0JC3bN22M55MYwAnm&gclid=CjwKCAjw48TUBhBREiwAK0GnQf\_Qj5TPFHHwshu6E9Yar2ypwlkMeHCGL7QV9c4pQILNQb-DTixeXhoCnpUQAvD\_BwE

Or any other options to prevent freezing?

Thanks!