I’m thinking they point the bows upstream and build a bridge between the hulls. Sort of a really big pontoon bridge. Believe it or not, the Persians did in 480 BC and it worked. Naturally you’d be able to navigate under the bridge between the hulls.
I think you’re on the right track. Draft is about 40..probably less when the superstructure, engines, and machinery are removed..sold for scrap..she’d ride higher...estimate now that the height from the waterline to the deck is about 100-120 feet..so depending on the bridge height clearances, they might have to elevate the roadway 50 feet or so above the deck.It’s doable, and probably at 1/2 the cost of building a cable-stay bridge...but there’ one obvious problem that I see. That whole region is very seismically active..so a quake...a tsunami..and the whole thing imitates Galloping Gertie..