This is EXACTLY what I was thinking of doing! I have been using Jiffy Peat Pellets buried in the center of the OF in the same manner as you had described, and it does ok. I think the mycorrhizae content in HF would be really beneficial to the younger roots too.
The day after sprout I transfer my jiffys to their final home, 5 gal airpots filled with a premoistened mix of equal parts OF/LW and perlite amended with organic granular poultry manure. Through trial and error this is my medium for zero defect auto grows.