I had that deadbolt in my Argosy. CanAmRV installed it; like you said, it's very low profile. Finding the keys is a pain though.
Here is the US supplier
for those deadbolts.
The key you need is sold through MBA USA locksmith supplies as well, a Borkey 545 IIRC. (I can't find that specific key listed on their website anymore, but I have ordered spare keys from them in the past.)
The key itself isn't that expensive, around $4, but you need to get the one with the precise profile. A local shop was able to cut it for me.