You probably should find a way to "move" the Modules to FastRAM instead of mirror them.... this will help a lot of People
There is always "NOMEMFKICK" as option to LoadModule which attempts that - this can be tried as an alternative as well. Problem is that this neither needs to work (if the RAM looses contents during bootstrap or is not auto-configuring) and that it also needs to keep exec in ChipMem.
The *real* problem is that multiple vendors do not set the attributes for their RAM correctly, or neither implement autoconfig correctly. Add on top that Ranger memory is neither suitable because the RAM-Test for ranger memory is simply broken in Os 3.1.
There is a tag for identifying suitable memory which is also used by default, but what can you do with all the multiple hardware on the market that did not quite follow CBMs recommendations (leave alone CBM, which did not follow its own best practises).
In the end, you never know what you get.