Carlos:

Maybe these pictures of the retract install on my US60 will help:

Picture 1: Shot of the bottom of my wing. Note the size of the wheel wells vs. the wheels. I will discuss this more below.
Picture 2: A (poor!) shot of the top of the wing, to give you and idea of where you'll need to mount the retract servo. (The servo you see further back controls the flaps.)
Picture 3: A shot of the retract servo installed in the wing. You can see how it sits so that the push rods operate just below the wing skin. In this picture, the pushrods have been moved far enough to engage the strut locks in the retracted position.
Picture 4: Another shot of the retract servo, beginning to extend the gear.

I measured the distance from the bottom of the servo to the top of the EZ connectors, and it's a little over 2 inches which (if my math doesn't fail too badly) is about 50mm. So you'll need that amount of depth in the forward portion of the wing to keep the bottom of the servo from sticking out of the bottom of the plane (or else you'd have to figure out how to mount the servo upside down, which I don't even want to think about). I also though about putting bends in the pushrods so the servo arm could sit above the top of the wing, but then threading the rods through the wing to the retracts might turn into a nightmare.

A couple of other things to consider. The wheel wells on the US are 3" in diameter, with 2" wheels. I'm not sure how much distance there is on a Tiger2 between the wing spar and the leading edge, but that will limit the size of your wheel wells. If the wells are too small in diameter, your wheels may hang up when retracting or extending because the landing gear struts will bend, especially if you're flying off a rough field or after a rough landing (but then you never do those, right? )

The wings on the Tiger2 are joined with a couple of small pieces of hardwood, but there's not an aluminum wing tube. And I think the center joint is wrapped with clear tape, but not something strong like fiberglass. If you have to cut away most of the center rib in front of the spar, you might end up weakening the wing joint, as well as weakening the wooden tab that holds the wing into the fuselage. There's probably enough room to mount the retract servo on one side of the center rib to avoid these problems.

Fred