As many seems to be reading this thread it may be worth mentioning that spending lots of money to get the perfect D65 simulator "just because" it's not a wise thing to do.
When you make dual-illuminant DNG profiles for general use the defacto standard (=Adobe standard) is indeed to make them for the StdA and D65 pair. This means that in order for the EXIF lightsource tags to match the truth you need to profile under those illuminants. However, they don't really need to match. The only thing they're used for is when deciding the matrix mix, ie if the temp is 4700K 50% of the 2850K StdA matrix will be mixed with 50% of the 6500K D65 matrix. To know the mix you need to know the temperature and to now the temperature you need to know the mixed matrix, a hen and egg problem solved by an iterative loop. But only after mixing the CM is used to derive the actual temperature/tint that is shown in the white balance tool.
To summarize, you can mismatch the actual calibration illuminant and its tag with quite wide margin before it will have any real effect. Therefore it's perfectly feasible to use real daylight as "D65" even if you make a dual-illuminant profile. (On single illuminant profiles the EXIF lightsource tag has no effect at all. ICC profiles are always single illuminant.)
Having a simulator adds convenience though, especially if you make many profiles or experiment a lot. It would not need to be a D65 simulator though, you could have some other average daylight.
It's still some advantage to *know* what light that has been used as calibration illuminant, if not the spectra at least the temperature. This is needed to make the DNG profile estimate light temperatures properly. (The CAT is also affected by that, but you can of course enable color constant behavior)
I have a hunch that for dual-illuminant profiles it's an advantage to get a bit above 5000K to get some more distance from StdA. At D65 we have very limited options on artifical light sources with nice spectral properties though. The Liulabs expensive filtered halogen does not have much competition. I'm curious about the UV-pumped white LEDs though, seems like Yuji is about to release one. With those it seems to be that the higher temperature the worse spectrum, so I'm not so sure the 6500K will look that good, but probably better then a Solux with 80B filter.