This one knows, yes, it depends on how much patience you have, @AndrejLeo.
Khajiit has wares ... if you have coin. Far and away the easiest way to accumulate furnishing plans is to simply buy them at the guild traders. May I recommend Baandari Trading Post for your shopping needs ... ?
But a patient Khajiit is a smart Khajiit, yes.
We cannot travel to the warm sands of Elsweyr until early June ... but this one thinks snooping around containers in Khenarthi's Roost and Reaper's March to "borrow" Khajiiti furnishing plans might yield best results.
Khajiit has only heard traveler's tales and rumors of a large Colovian habitation in Reaper's March named the 'Vile Manse'. This one will not go there. But you look like someone who might.