I have to say I respectfully disagree that LE slats, in model scale, will not lift their own weight.

I have attached a graph of Coefficient of Lift, of an airfoil, with slats, and with slats and flaps.

Now the lift equation is

L = Cl * A * .5 * r * V^2

Flaps alone increase CL (and therefore lift) , AT THE SAME ANGLE OF ATTACK.

Slats increase CL (and therefore lift) by allowing a greater angle of attack

Both of these statements assume enough power is available to overcome the extra drag created by these devices.

Therefore it looks to me like slats can double the lift, and that would easily accommodate their extra weight.

It will also allow you to fly slower at the same lift, but not as much as the velocity term is a square law.