I would add the flaps but I would give myself some method of adjusting their total throw - Start with a small amount and add throw after test flying.  If you don't like them, you can always connect them to a non-moving point.

I suspect that with that real low wing, there will be a lot of nose-down pitching added as the flap deflection goes up -

Start with lots of altitude and at low throttle and realize that if you are very nose-heavy, it MAY be difficult to keep the nose level when the flaps deploy.

Of course, it may also just bore straight ahead or balloon up when they drop but give yourself the wiggle room.

You can do that. In the day there was a forked release rod for the flaps allowing each one to drop onto an adjustable stop that was accessable from the belly of the plane(in this case it was a Sterling guardian) adjusted by a screw. We also had the inboard flap side stop a little higher to give an aileron affect. I dont remember who should be credited for that but it was a common trick than. Worked fine so I will have that in my next CL 1 or 2.
Wayne

After watching stunt models do their perfect nice slow landings with the flaps inter acting with the elevators I tried it on a Sterling Guardian. It worked fine. When you throttle down you give a little up elevator and the flaps go down a little. The slower you go the more elevator is used and more flaps. At your slowest speed the model is flying pitched up some with nearly full up elevator and full down flaps. If you get in trouble a little and goose it the flaps come up as the elevator goes to neutral and you don't get the wild gyrations you get with the power on and the flaps still full down.Worked for me!

Make sure they are tapered, meaning the MAC of the flaps is in the same location as the MAC of the wing.
If you made your flaps constant chord, funny things might happen when you lower them as most of the flap surface area would be way aft of the CG (swept wing).