Seeking Antenna/Setup Advice for Hilly Terrain (PA) – approx 3-mile radius

I’m looking to build out a Meshtastic setup in a very hilly part of Pennsylvania. I’m trying to establish a reliable mesh covering about a 3-mile radius around my home base, but the "ridge and valley" geography here is making me second-guess my hardware choices.

​Current Gear: ​Nodes: Heltec T1000e (for EDC) and a RAK Wireless WisBlock node. I also bought 2 v3 helocs that are in route. ​ I am planning to mount the RAK node on a mast high above my roofline to clear as many obstacles as possible.

​These are the things i need help on.

​Antenna dBi: Given the hills, should I avoid high-gain antennas? I’m worried an 8dBi might overshoot the valleys. Would a 3dBi or 5.8dBi be better for "filling in" the lower elevations? ​how many nodes/repeaters are typically needed to reliably cover a 3-mile circle?

​Should I look into placing a dedicated repeater on a nearby high point, or will my roof-mounted RAK node be enough to act as the primary hub? ​ ​I'm relatively new to this and want to make sure I buy the right components the first time. Any advice from people living in similar terrain would be greatly appreciated!

​(Note: I used an AI to help me structure this post and technical questions to make sure I was being as clear as possible.)