Apologies if I'm not understanding properly, but what I'm interpreting is that you want to take 2" (50 mm) thickness off the wide face of a board with a really big router cutter. Is that correct? If so, a few things.
- As noted, it's in your best interests (for all kinds of reasons) to take small amounts of material off in a pass.
- To spin a large cutter like that requires a big router. My suspicion is that it would kill a cheapo machine. There's not that much advantage to having such a large cutter. (And it would probably be expensive...)
- If the reference face of the wood isn't flat, then this method will reproduce that out-of-flat-ness in your finished work.
Again, I might be misinterpreting, but this doesn't sound like good use of a router.
If you had to do it with a router, you'd probably want to cut a bunch of grooves with ridges between that would support the router in subsequent passes. (Hint: don't leave a ridge at the very edge...) Then you'd shave off the ridges with a chisel/plane/whatever. Since you have a lot of material to remove, this would be a multiple step operation (and a really boring one, at that).
The handheld planer idea is a good one. Again, take smallish bites. If you found someone that owned a thickness planer and convinced them that there wasn't any foreign objects in your wood, then they might do the job for you.
Good luck!
Nigel