Highly correlated spectra should not hurt DCamProf profiling as it's designed to deal with such cases, but on the other hand it will not help much either. They're handled as averaging a bunch of patches into one, unless you reduce the chromaticity grouping distance to zero then it will try to correct for each patch (and result will not be good).
DCamProf currently makes no use of a neutral step wedge (it sees it just a bunch of highly correlated spectra), as it assumes the target shot is linear. Not sure yet if that's a good idea. Shots with glare issues are certainly not linear, but I've thought that those cannot be well corrected anyway so better require a glare-free shot. Even with a target shot made with proper lighting in a dark room maybe there can be some residual glare than needs correction though, or if the spectrometer measurement suffers from glare one needs to correct the other way around. Not sure though if a simple spline curve lightness correction is relevant.
Interesting to know that 2.5D LUTs are used in repro work too, and yes when the lightness adjustment is spectrally flat is should indeed work out fine. If you like DCamProf can make 2D LUTs too by relaxing the L dimension maximally (say -l 1000,0 to make-profile).