although it limits its run-time environment quite a bit, if it runs only with CT TOS.
As there is only one 060 environment and that is the CT60TOS, I wouldn't worry too much about it. :) Even FreeMiNT reuses CT60 TOS's built-in emulation. The situation is different for 040, though - there you must always load all the patches manually.
In larger demo one might include a pre-calculated lookup table to
make it more compatible. Or if that lookup is too large, use a
smaller pre-calculated one and calculated larger one at run-time
e.g. with linear interpolation?
Sure you can do it but one of the advantages of using 060 is the built-in FPU (as you can see, the EC/LC models are not even considered as worth supporting in Atari/Amiga world). So really, Hatari should better starting supporting CT60 TOS and/or the FPSP if it aims to run 060 demos one day. :)