Aaaaaand the conversation ends. If you're going to suggest ignoring what's already been set out as the ground rules and encourage further lore butchering, then there's not much more to say, resource demands aside.
And on those resource demands, even if you want to segregate up the pairing:
(5x5) + (4x4) + 2 == 43 pairings, assuming potential interbreeding of [Altmer, Dunmer, Bosmer, Orsimer, Breton (Half-elf mongrels)] and [Redguard, Nord, Imperial, and Breton (half-human mongrels)], plus Khajiit and Argonians. However, Khajiit stem from the http://www.imperial-library.info/mwbooks/clanmother.shtml as the elves, much the same as the Orcs do. So if you account for that, the formula looks like this:
(6x6) + (4x4) + 1 == 53 pairings, with interbreeding of [Altmer, Dunmer, Bosmer, Orsimer, Khajiit, Breton] and [Redguard, Nord, Imperial, Breton] plus Argonians.
Either way, you're going to have massive dilution to the quality of all the races. Which is not OK. You want hybrid races? Do what DagothJeff notes, adjust the face shape and tone values for one of the stock races and roleplay. The racials aren't going to need adjusting thanks to the already-defined methods of different-paired reproduction which you show such contempt for.