There only one good solution I’ve seen in use up until now: long handlebar with aerobars. I’ve got lots more to say, and lots of ideas, but I’ll save it.
Back on topic, if you’re just holding on the handles, and not using the side bits, it doesn’t matter where they come from. Could you have a stem in front and then a really wide handlebar with bar-ends? Then you’d be giving up all hope in the event of a forward-upd, but only in the same sense as you would for backward-upds the other way. Maybe in either case some sort of safety-release is possible? Most of the force on the handles when I ride is forward and down, though I do pull on very steep uphills. On a side-handle system I’d give that up for a safety mechanism.