Tbf, I think Nervous map is a strong start. It offers a bit of everything, from city living to the opportunity of small city living, from Saint Denis to Valentine and Strawberry plus the territories between. That offers everything from the swamps to the mountainside living.
To be fair, I find the outlined area as a good start for scripted buildings and stores. It allows for a bit of everything, though it would be cool to have Annesburg included too. -EDIT- Reason Annesburg would be cool, is that it is a small industrial town and it has a lot of small cottages which would be very cheap housing, as where Saint Denis which is also an industrial town has far more nicer districts and areas, which means there's fewer cheap cottages.
Which is why we should also make a "meet-up" rule in my opinion. If two players are aware of each other and know each other or have had interactions, it should be allowed to poke them on Discord and say "Hey, we both frequent this area, are you gonna be on tonight and are you gonna be able to RP?" - I know it might seem a bit MG'y, but honestly that'd solve a lot of the early days problems. Also, I do apologize if I went off topic, if needed I will post it as a suggestion.
I think all the points you are making are extremely valid, I also think that voice RP mostly caters to people that might stream or do YouTube. Personally it'd scare me off the server, since I'd be uncomfortable with the whole voice RP as well as the limiting factor as you also mentioned. It'd force me to only be able to play a Scandinavian immigrant, and this is my argument why. Could I pretend to be American? Sure, but people would not understand some of my pronounciation, which would give off a unserious vibe perhaps, as well as it'd limit my vocabulary. When doing text RP it is much easier to form a sentence and use a wider vocabulary as you have a second to think about your action, where as in voice RP the response expected is imminent and not thirty seconds from now, as it'd only slow the pace down and make it less genuine, at least in my humble opinion.
I haven't played the game too much, so my opinion might not be as warranted as those that have played a bunch, but I honestly think that as soon as the server hits a stable 150-200 players, the entire map should be opened up, or players should perhaps be allowed to buy remote cabins or such should they wish for that, since the period is the last part of the "Wild West", even though it is dying out, in part due to the ability to move quicker over longer distances than previously, which in turn made the vast lands once considered the Wild West a place where you'd likely be able to run into a person again, instead of a place where you could risk never seeing the same person twice, but I still think that the scarcity should play in and perhaps that when on the road, you could risk travelling for a while, never seeing another player. Players will still connect around the main hubs and probably decide to keep their RP in those general areas, but for starters I think possibly limiting the "hub" to a certain area could be a good idea.