I'm running 4 700' horizontal loops in NE OH. (You can see my thread here https://www.geoexchange.org/forum/threads/starting-diy-horizontal-closed-loop-in-ne-ohio.7552/) They are 5' deep. Deep earth temp here is about 53*. I have them hooked to a 3 T Q Energy HP. My entering water temp bottomed out at 40* (we do supplement with wood on the colder days.). I'm running 10 gpm. I would lean more towards the 2 gpm per loop and add more loops. Your pumping power goes down, your loops can be longer with less pumping penalty, and your potential heat stored in the loops when HP is off is higher. My unit can run for nearly 10 min before turbulent flow starts to matter due to the oversize field. Then the fluid takes longer to go thru the ground so has more time to pick up heat. All in all, the size of the field is far more important than turbulent flow (at least with 3/4” pipe).