What's MMMV? Google isn't helpful at all.
(
My Mileage May Vary - slightly more self-doubting than the typical YMMV, is how I intended.)
N-S orientations (and vice-versa) work well enough with the end-shade, IMO, I see. The one-tile E-W extended bridge works well (obviously just one tile
and extended), and so does the N-S equivalent (though the shade loses out, slightly, I don't know how you can prevent that, as is, and it still works with other hints).
If you feel the need to add a span, make it a whole-span. Ends with 'flavour-wedge'[1] to support the general profile of a skewed-up/-down flooring (obvious by profile, when side-on, and shading) and just a continual underside layer (and shadow-effect, which is essentially what remains as a raised 'ghost bridge') that doesn't even try to 'sink piers' down that don't exist.
For multi-pier non-retracting bridges, they'd be best to be
procedurally built with mid-stream piers, with full actual archetectural[2] structures.
I speak only as one who knows (somewhat) how the game actually works, though. I cannot say how a newcomer might react to impossibly-slender depictions, if you refrain from this little graphical 'lie' to maintain a surrogate verisimilitude. But given you can run a raising bridge half way across a 'bottomless' gorge (dry, and dug deep enough to fade out into mist any obvious bottom) to be met
from the side by another such bridge sent out from the opposite cliff-edge (L-shape or Z-shape pathing across the ravine - incidentally needing wagons to cross the stake-and-rope-edging(s)!), this would render such aesthetic renderings even odder in appearance. So unless you're catering for the examples shown (simple river traversal) as separate treatments to the 'simple slightly elevated bridge' then the effort might be wasted.
IMO. Always IMO, naturally. (Just because I put a lot of words down about it, now, doesn't mean I'm right. It's just me inefficiently explaining what's in my head, given I lack your obvious ability to use single pictures in the place of those thousand ill-judged words.) I claim no more authority than a buzzing mosquito!
[1] Technically, such an abuttment should be far more substantial to look 'real', but given you can run a 'floating floor' across the entire map from atop a single support, we can't begrudge you not bowing to the otherwise ignored physics of such long-low arches across a mere ten-ish tiles with supports probably at both ends.
[2] Something for Tarn to do, if at all... you'd just be graphicking resources to fit with loads of one-tile arches (or lintels, as per clapper-bridges) between supporting pillars rising from the riverbed, which is probably already within your graphics palette without any tinkering.