Just a tho't. . . Why don'tcha get enough old vehicle license plates to make say a 3' square arrangement. License plates are quite reflective and have been used to more consistently determine range with LRFs.
Kind of tough to drag around, and may not be functional. But I'm one of those guys who's gotta try.
I may be the slowest guy on the mountain . . . . but . . . . I'm on the mountain!
As far as rangefinders go, i bought a leica 1600 from europtic for $650 a couple months ago. U won't fet much better value than that. I am in the process of getting set for long range also and determined that about all other things the first thing i needed was a good rangefinder that is rated beyond the ranges i am wanting to shoot