I'm in the Mark Twain National Forest. Don't know about repeaters
but if I had to guess, 50-100 miles away from me. Well holy carp, there's one in the town that I would be trying to do comms with. Might be that prepper community. Looking to someone's repeater google map, it looks like that town but looking up his call sign, same city as me for mailing address but that other town isn't really a town so it probably uses my city as a mailing address. When I say city, I use the term loosely. Same with town really. Our Post Office is a 10x20 room in the general store and they're open half a day, run by one person. The town I do my grocery shopping at has PO boxes in the corner of the grocery store. That's for all the people that USPS won't deliver to. They won't delver to a buddy of mine 6 miles away because he's the only one on that 10 miles long road and he's centered in that 10 miles. He gets his mail at that grocery store which is technically in another county.
Looking at a topo map, he's a little lower than me and there's some knolls in between that are a little higher in elevation. Depends on how accurate these online maps are. The personal google map of repeaters is off compared to his address on google maps. Enough so that a knoll may or may not be in the way. Gonna run out there now and see if I can find a tower. It's 5 miles away.
This gives you an idea of the terrain. My location is at the higher of the bold lines in the green area and his is almost that high in the white area, depending on his tower location. I'm close to centered, just NW of little bitty knoll and he's N/NE of me in that white neighborhood looking area.
Could a repeater be powerful enough to overcome a 20-50 foot tall knoll and/or trees in between me and it if I have a low power unit(handheld or mobile) and no tower?
Repeaters are usually installed at high elevations, either towers or high terrain. Here in NW Wa (Puget Sound) they are up on mountains so they are easy to reach by handheld. I would love to live in the boonies like you :)