I checked the LRO images and you're right: the albedo of the lander is higher than its surroundings.
Here is a Lunar Reconnaissance Orbiter image of the Apollo 17 landing site:
I found several places where the telescope size is calculated to resolve the LM. Phil Plait (in his Bad Astronomy blog) arrives at a telescope size of 100 m to do this.
Just seeing a bright dot requires less resolution than this. Reusing the calculations from here and doubling the telescope diameter to 10 m, I get a resolution of 23.2 m. So in your telescope you see the average color/brightness of a square of 23x23m.
I did a quick and unscientific test, grabbing a roughly 23x23 m square from the above photo and scaling it to 1x1 pixel, then checking the grayscale value of that pixel. The square with the lander in it was darker than an adjacent square, so a 10 m telescope wouldn't see a bright spot where the lander is. It looks like the lander's shadow pulls the average brightness down to a level that's not reliably distinguishable from the surroundings.
Here is the above image downsampled to 16x12 pixels to get a pixel size of 25x25 m, then upscaled to 400x300px to get an image that is easier to view than a 16x12 px image. As you can see, you can't distinguish between the variations in albedo due to shadowing and variations caused by the LM.