10 gallon crabitat build

So, I am finally getting my crabitat going. I have been gathering stuff to get it all put together, but somehow it just kept getting put off. Not Anymore. lol
Anyways, here is what I am planning on doing:
10 gallon tank with mostly sand (play sand) and some gravel on the bottom, with a few inches of water on one side. I have a couple DIY tunnels made from pvc, that I am going to hide in the sand. I plan on getting a coconut to make a crab clubhouse in one corner.
I have an internal filter, Penn-Plax Cascade 300, that I am going to hide behind a rock waterfall I am currently making right now. I have a small piece of driftwood I'm going to stick in there too. I need some suggestions for some plants. Is there anything I can put in there since I'm not going to have a lot of water?
I have taken some pictures of the process and will try and get them up after work in the morning. I work nights, so as soon as I get outta here, I'm going to get started again.
:feedback:If you have any suggestions please let me know, since I have never built one of these before, any help is appreciated.
Dereck

How do I figure out which ones I am getting? They are they ones at the LFS but they don't have the scientific names posted, not to mention, I can't find a list of species for fiddler crabs that have pictures with them. Maybe I will stop at the LFS today and try to get some info on them. Maybe I won't do any plants and just keep it simple for now. From what I have read about them they are most likely going to shred them anyways. I know they are just the regular crabs that are always at walmart. Though I will not be getting mine from there.

Also I was thinking about the stock and m/f ratio...do you think 2m/3f would be pushing it in a 10 gallon? I am going to start out with 1m/3f, and get another male down the road if everything is going ok. What do y'all think?

Ok, so I have been pretty busy lately but I did get to work on the crabitat a little and figured I would update with some pics.
I have to go get a different filter, the one I was going to use isn't going to work out like I planned so I need to exchange that tonight. I did build a rock waterfall but it looked horrible because it started to fall apart halfway through. I gotta re-think this through.
But here is what I have now.

What do you think?

I bought a coconut and made a crab hut that is in the back right corner and repostioned the tunnel because it was below the water line which caused the sand to start flowing into the tunnel. I know this may happen regardless since the fiddlers like to borrow, but I am hoping they won't mess it up quickly at least, cause I defintely want to get some photos of them in the tube if I can. I'm think I may have to scrap this whole plan of a rock wall around the filter since I can't seem to get it to work how I want it. Maybe I will just get a few good sized stones to place under the flow of water. I am just trying to find a way to limit splashing, because I don't want to disurb the sand and gravel too much if possible. I will update with pics as soon as I figure it out.