While it's possible dosbox may take a few shortcuts in it's emulation which may cause win95 to fail (haven't tried it myself)... are you aware Win95 is just a big fat-arse dos program?
As it happens, this is something which I followed very closely back in the day.
Almost exactly 10 years ago, Caldera tried to do this very thing... their aim was to get Windows 95 to run on top of DRDOS. From what I recall, Windows 95 boots DOS first, and then modifies the DOS kernel in-memory (!), patching the OS functions like 'open file' etc so that they are intercepted and emulated by the win32 kernel.
For this to work, it means that the DOS kernel has to be the right 'shape', i.e. this particular instruction has to be at this particular location, all the internal data structures have to be the same size etc, or it will end up inserting the patches in the wrong place and it'll just die. That, IIRC, is also why you can't run Win95 SP1 off the SP2 DOS kernel, or Win98 off the Win95 DOS kernel etc - they have to be byte-for-byte compatible.
For some of the gory details about the code patching, a good book on the subject is 'Unauthorised Windows 95' by Andrew Schulman, if you can find it.
Long story short, Caldera did manage to make a version of their kernel that booted Windows 95, but it wasn't something that could easily be generalised. Likewise, if you had a team of incredibly talented people, you'd be able to make DOSbox interface with a specific build of win95 (and no other), but it probably wouldn't be worth the effort.
