To hell with disapproval, I have a lap harp a bit too big to hold without support. One harp maker has a product they nickname "the harp bra", a couple of cloth cups and some velcro straps. At $25 I thought it too much, so I went to K-Mart and got a nice red satin 32B bra for $2.95 (took my wife, so I wouldn't be picked up as a "prevert"). A bit of cutting and sewing, and some Home Depot velcro straps, and I have an effective support for the harp which is a conversation piece. Total cost, five bucks.
Not that this is a direct answer, but I think RT has already said that "whatever works" is right for you. I'm sure that the old players would have used whatever was best for them and not worried about the particulars. Best, Jon