TL;DR Description:
This is a set of post-epilogue save files with most side content still intact (hat tip to TheRaptorMovies whose save bundle is linked below), most items and tonics removed, and user-definable starting cash ranging from $20,000 to $0. See below for the full range of starting cash options. I believe these saves are as close as we can get to creating a "RDO-like" experience in the single player story mode, especially if you start yourself off with very little cash.

*Addendum Note: I forgot to mention, though I removed most of the goods from John's inventory, I actually purchased 50 units of hay for the horse (Legend of the East Satchel, of course). It's just a personal preference. Horses can graze and don't require you to carry around hay for them. So I always keep a ton of it on hand and just role-play that they're grazing.


Version 1.1 Description
In addition to the versions described below, version 1.1 contains an extra save file: The Pauper Edition. In keeping with my theme to create the best possible "RDO-like" experience that I can using a single-player save, it seemed prudent to include the Scrawny Nag. The closest we have in single-player is the humble morgan. Rachel the thoroughbred was sadly given to another family of homesteaders in exchange for some much needed seed and livestock at the Marston ranch. They threw in a pretty little flaxen chestnut morgan so that John wouldn't be without transportation. Additionally, more weapons were removed from John's inventory so that now he only has a couple cattleman revolvers and a carbine repeater. He won't be getting too many perfect pelts without a proper rifle or varmint rifle, so this will make the beginning stages a little more challenging (you may want to do some bow hunting until you get a proper rifle). And finally, this edition starts John with no money at all. This version is recommended only for players who love being poor and want to work themselves up literally from the bottom.

Full Description
TheRaptorMovies uploaded a fantastic save bundle allowing players to start at any quest from Chapter 3 to the Epilogues to the end-game free-roam. You can find it here and please read for further details:

RDR2 Save Bundle (Chapter 3 to Epilogue End) High Honor and Minimum Completion
https://www.nexusmods.com/reddeadredemption2/mods/440

The best thing about these saves is he did as little side content as possible, allowing players to start at whatever point they wanted while still preserving most activities.

I thought it would be useful to work with his final save to create a better post-game experience. As I see it, the post-game has three major problems (Skip 1-3 if you don't want light spoilers):

1) Unless you use extreme restraint like TheRaptorMovies did, it's unlikely you'll have much content remaining by the time you finish the epilogues.

2) You're given way too much money. This makes money meaningless in free roam.

3) The game seems very lonely and empty going from a camp filled with characters to a ranch with just Abigail, Jack and Uncle.

Using TheRaptorMovies' post-epilogue save file and a couple mods from bolmin70, I was able to remedy numbers 1 and 2. Of course there's not much we can do about number 3. However, the preservation of much of the side content ensures that John will still meet people and have cut scenes, making the world a little less lonely.

This mod bundle starts you off with very little. Your wardrobe is small and you only have John's thoroughbred horse "Rachel". Also, I removed most (but not all) of the guns from John's inventory using this mod by bolmin70:

Selling Guns
https://www.nexusmods.com/reddeadredemption2/mods/245

I also removed most (but not all) of the food and tonics left in TheRaptorMovies' save. The re-acquisition of all these things will serve as a nice money sink, immediately giving the player something to work toward. Hat tip to bigshot103 for his save game which served as the inspiration for this, found here:

Sandbox Savegame
https://www.nexusmods.com/reddeadredemption2/mods/439

Finally, this is called a save "bundle" because there are several versions, each with increasingly less starting money for John. To accomplish this, I used bolmin70's mod found here:

Banking The Old American Art - A Banking Mod
https://www.nexusmods.com/reddeadredemption2/mods/228

*Note that this banking mod is NOT required for these saves to work.

Players have the following choices for their starting cash:

$20,000+ (This is untouched from the default post-epilogue)
$15,000
$10,000
$7,500
$5,000
$2,500
$1,000
$750
$500
$250
$100
$50
$25
$0

I personally recommend starting with $100 or less so that money becomes more important. This way you really have to work to build your wealth. All the side-content, the hunting, fishing, gambling and robbing (even farming if you don't mind working for pennies) become that much more important.


Recommended Mods:
Any of bolmin70's mods help to enrich the experience, especially in the post-epilogue which isn't as content rich as the main story. You can find his mods here:

https://www.nexusmods.com/reddeadredemption2/users/37378325?tab=user+files


Thank you to the following people:
TheRaptorMovies
bolmin70
bigshot103
The Nexus management and staff
Rockstar Games for the greatest game ever made