To use Rhino generated SVG you should after exporting to SVG edit the file and remove the <defs/>
tag remove the stroke related attributes from the path
tag. Looking at another font it looks like fill
attribute is set to currentColor
.
So essentially one character SVG becomes:
<?xml version="1.0" standalone="no">
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd" >
<svg version="1.1" viewBox="0 0 141.6 141.6" xmlns="http://www.w3.org/2000/svg">
<path d="your path coords here" fill="currentColor">
</svg>
</xml>
You probably should ensure the viewbox is correct for one character as well, didn’t look into that much yet. I should read the FontForge documentation for that I suppose 
Anyway, Rhino exports a curve with several stroke-related attributes as part of the path
tag. Removing those ensures only the curve itself gets imported instead of a double curve.
You probably could write a script that does the SVG export, then directly edits the file to adjust the SVG, removing stuff that isn’t necessary.
edit: after some reading, looks like a 1000mmx1000mm setup with horizontal base line at 200mm is something to start with. Draw your glyph in that area, then during export set to 1000mmx1000mm and 1:1 scale
Exporting with these settings
generates the SVG file
<?xml version="1.0" encoding="utf-8" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg version="1.1" width="2835pt" height="2835pt" viewBox="0 0 2834.64 2834.64" xmlns="http://www.w3.org/2000/svg">
<defs />
<g id="Default">
<path d="M1995.575,714.6525 C1436.2021,691.50604 1026.317,854.4956 765.9194,1203.6213 C505.5218,1552.7471 497.80627,1819.8958 742.77295,2005.0674 C987.73956,2190.239 1203.7732,2242.3186 1390.8737,2161.306 C1577.9742,2080.2932 1751.5726,1855.5798 1911.669,1487.1654 C2071.7654,1118.751 2158.5645,877.6421 2172.0667,763.83875 C2185.5686,650.03534 2206.7861,612.4223 2235.7192,650.99976 C2264.6523,689.5772 2275.2612,1177.5815 2267.5457,2115.013" stroke="#000000" stroke-width="0.24" stroke-linecap="round" stroke-linejoin="round" fill="none" />
</g>
</svg>
I edit this to be
<?xml version="1.0" encoding="utf-8" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg version="1.1" viewBox="0 0 2834.64 2834.64" xmlns="http://www.w3.org/2000/svg">
<path d="M1995.575,714.6525 C1436.2021,691.50604 1026.317,854.4956 765.9194,1203.6213 C505.5218,1552.7471 497.80627,1819.8958 742.77295,2005.0674 C987.73956,2190.239 1203.7732,2242.3186 1390.8737,2161.306 C1577.9742,2080.2932 1751.5726,1855.5798 1911.669,1487.1654 C2071.7654,1118.751 2158.5645,877.6421 2172.0667,763.83875 C2185.5686,650.03534 2206.7861,612.4223 2235.7192,650.99976 C2264.6523,689.5772 2275.2612,1177.5815 2267.5457,2115.013" fill="currentColor" />
</svg>
This imports as
edit2: actually, better to export with Window, then you can select the 1000x1000 area as the export window. That will ensure the character is correctly in its glyph box