Yeah people candyflip on LSD/MDMA all the time. IMO the best experience is taking the MDMA roughly 3-3.5 hours after the dose of LSD so you are coming up after the crest of the LSD peak. Peaking on both at the same time has been fairly uncomfortable IME.
Personally I only do this stuff at EDM shows as anything else, minus MDMA and couples therapy, would be a waste so I personally wouldnt want the sedating effects of DMT in that environment and the LSD/MDMA is incredible enough as it is that I would never see a reason to add anything else. That said, it wont hurt you