if you're not performing your min speed will be Vmca
That would be a silly proposition, I suggest. If you are not performing around blue line, then you will be going down faster at TOSS and (possibly very much) faster again at Vmca. In a nutshell, one ought never to be contemplating reducing speed below TOSS other than for a Vmca demonstration (and that ought only to be done for an initial twin endorsement) .. silly strategy and just increases the risk of converting a controlled crash landing into a fatal.
It is the height of folly to set yourself up to convert a salvageable situation into an inflight Vmca departure and subsequent fatal ground impact.
I once flew a 404 that was fitted with a IAS that was for a chieftain
There are rules for the maintainers but it doesn't help if they are ignored. However, the AFM will cite the relevant speeds so there is no excuse for simply not knowing what the book speeds are.