X2 on the anchor trolley running the length of the boat, or as much as you can do so anyhow. Makes a world of difference with boat positioning as FH stated.
FWIW, I got all kinds of stuff to rig out my boats initially, but I hardly ever use any of it. Plus it kind of defeats the purpose of getting a yak in the first place IMO.
Keep it simple I say. Anchor cleat to go with the trolley, maybe 1-2 extra rod holders if you like to have multiple rods on hand, quality paddle, etc.