Can you call a table that stretches across a room, almost from end to end, a "room-width table"?
Table
Yes, although it would be more common to phrase it as "a table as wide as the room".
If you use [room-width table] in speech, you will be asked to repeat it.
In writing, it is more likely to be understood. But it will appear unusual.
In writing, it is more likely to be understood. But it will appear unusual.