A riser is really not much of a challenging project, if you can build flat and level.
I would indeed explore tearing things down a bit at the entry, mostly to introduce sheet metal HVAC, in order to clean up the ceiling, and save inches of height.
I'd also explore maybe just doing a simple 3 seat room, which maybe doesn't seem to be much of an option for people here on AVS, but if all one sees, is multi-row and
large rooms, then I expect that ends to skew the want list to what might be an extreme for a smaller room.
I do like this WaterFall Audio based theater for what could be a pretty nifty base to look at such a space. It also wouldn't exactly be expensive nor complex to build, nor all
that difficult to put one's own look on such a layout.