I just looked at both the Heritage manual and the online info about the Heritage at the Hearthstone website.
Appears the manual is not up to date.
The website says (and I almost quote):"The updated look of this whole house heater with taller legs now only requires ember protection."
So, if you exchanged for a Heritage, you'd only need ember protection, as long as you made sure you got a current model with the longer legs. .
The "documents" section with schematics does not show the overhead view WITH the stove on a heath pad, as the Mansfield and Homestead schematics do. But, going from the manual and required cleanace to combustibles:
with the heritage you would need 7 inches at the rear to your combustible, the width of the BODY of the stove (and they bold BODY, so you don't need to worry about the legs, which makes the stove deeper), which is 18 3/4 inches. and then 16 inches in front of that for hearth protection for the glass, equals a total of 41 3/4 inches unless I am wrong somewhere.
So I think the Heritage would fit on your hearth as is? I've not quite got your pipe exit clear in my mind, but it is quite common to use an adjustable bend to move pipe closer to or further from a wall. I'll reread your post and see if I can picture your set up neaar where it exits. Be surprised if you can't move the pipe closer to the wall so it can be where the Heritage would require when installed as close to the wall as permitted.
Edit: Sounds like a simple horizontal exit. I can't see why there would be any problem moving the pipe closer to the wall and using an adjustable 90. You have a few inches to work with anyway, I think, since your requirement with the stove 7 inches from the wall is under 42 inches, and I think your hearth is effectively 47 inches. If so, the stove could be as much as 12 inches from the wall if you wished. In a narrow room, I'd try to get it as close to the wall as reasonable, as it makes the room feel bigger.
If I've got all this right, I'd be exchanging for a Heritage. It'd make your life easier. And it sure wouldn't have any trouble heating your home. You might actually be more comfortable. I'm a bit concerned that Homestead may throw a ton of heat out the window.