vee bottom or cancaves for small wave mid length board east cost Australia.
Both.
concave mid for lift.
V tail for turning and projection.
Flat nose for least drag.
Concave through the fins, will loose drive, but side slip and be looser.
Concave under the feet will increase speed, but only if “pumped”.
Vee is like a “pre-fin” It will be like the same fin, all other things equal, feels larger.
Vee will roll rail to rail easier, but like the similar design the hull, will do less directional change when rolled on rail. Vee will feel more stable under feet.
Concave will be more unstable with chop or backwash.
And of course, everything in balance according to rider and preferences.
Wide boards with concave tend to be stiff, then spin out.
Narrow boards with concave tend to get extra lift.
Wide boards with convex, hull, tend to be easy to lean out and turn hard with power.
Narrow boards with convex tend to ride smooth, never get going, but extremely easy to bank over, then stall.
the right things in the right place for the specific wave type and individual its designed for…many many variables to consider…
Small waves, mid length, go flat. Wont hurt.
Small waves, mid length, go flat. Wont hurt.
I’m with Beery on this one, small waves means less power and the more contours you have the further along the board the water needs to travel (i.e. more wetted surface). the easy water can flow off the board the faster it will go.
My 5’10" fish I made using Steve Lis’ template and bottom flies in small stuff, it has flat bottom with slight bevel to rails (3/16 lift about 4" wide), I put a slight into panel V in the tail to help with rail to rail but the contours are smooth and continuous through the bottom, no bumps or humps for the water to negotiate.
Simple is good 
See the problem here?
A Lis fish is usually around 22" wide. Is your proposed board that wide? And is the tail of your board going to be around 17"?
Conversely, if you were making a small wave board at around 18.5" wide, you'd be committing suicide if you don't add some slight concave to the equation.
SLIGHT concave.
And if you were making a 25" wide small wave board, consider a hull shape. Don't need more lift, need some turning control there.
Generally, for “performance” boards, I go single concave…
Flatter rocker, shallower concave.
Curvier rocker, deeper concave.
More tail kick, less or even no vee (flat behind the trailer).
Flatter tail kick, more vee.
Narrower pod, less vee
Wider pod, more vee…
None of this applies for fish.
Small mushy waves, flatter rocker, shallower concave, wider tail, more vee.
Small punchy waves, curvier rocker, deeper concave, narrower tail, less vee.
sofr small waves id say reduced rocker n a flat bottom for speed n ease of getting into waves
if it were me, I’d go convex belly then slight vee infront of the fin(s)
do you have an outline, or dims for it yet?