I just measured a TT bike (FELT DA2) of mine along the chain stays.
It is 80mm wide. The cranks are 15mm wide.
115mm wide Q is possible on this 11speed bike.
But it measures 145-150. This is a BB30 and the SRAM Red cranks flare out. They clear the chain by 5mm. Unlike chain-stays that flare, the chain is straight.
The MFGs could do 120Q with the chain on the middle/inner cogs. The cassette could be closer on a composite (disc or trispoke) wheel.