Funny, I'm just the opposite--I don't slap much, but the first time I played an old Warmoth Big 5 (2-3/16" at the nut), I found myself thinking "This is what a bass should feel like!", and it was really confirmed when I got my first Curbow 5 (20mm spacing at the bridge). So, those are the specs for my upcoming Dola 5...
Still have that Curbow 6? I wanna say I thought the neck was about as wide as my CB 7 string. Maybe a thinner back profile if I remember correctly.