I'm sorta new around these parts and I was hoping I could get some expert help for my tank. I currently have a 20ish gallon, but am hoping to expand very soon! I'm constantly checking Craigslist for a decent tank 50 gallons or bigger if the price is right. Currently, the crab, a massive jumbo PP, in the tank has VERY little room to wander around, but his conditions are all perfect as far as I can tell.
The temperature/humidity is 80/80-90% he's got big salt/freshwater dishes that he can easily submerge in and exit at will, a clay pot moss pit I've recently installed ( I was having some trouble with humidity but it seems to be clearing up perfectly. ) a few shells and his food dish ( all natural highly nutritional diet that i've researched extensively ) as well as a few branches and a cuttle bone. So, you guys can see the size issue i'm facing here
I feel bad, but I'm working very hard to get him into a better tank asap. Given these specifications, is there anything else I can do for him in the meantime to ensure optimum health and zero stress? He's a pretty easy going guy, but I'm something of a worrywort. I don't want something bad to happen before I get the tank! The substrate is all playground sand of sandcastle consistency ( I know coconut fiber is recommended, but I've had really horrible luck with it. )
I was also looking into foliage and decor. A lot of crabbers seem to use silk plants, but I know how sensitive hermies can get and I was worried that there were chemicals used that could harm them? He needs more of a place to hide, and I thought that some sort of plants would be a good temporary solution around the mosspit and everything else.
The escape proof paper weight's name is Tobey -- don't mind him.
UPDATE; The moss pit was traded out tonight for his old clay pot hide that I've tipped over on it's side and filled with moss. We decided to compromise.
This is just a size reference of him vs. the tank. He's in the same shell in the previous shot.
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Now. I'm going to address one more thing before people start throwing things at me. I know this is the wrong forum in which to bring this up, but I thought I'd go ahead and clear it up really fast -- I've been told this MULTIPLE times and I know it's the cardinal rule, however -- he's long outlived numerous tank mates and at one point, I was under the impression he was killing them. After a lot of research, I figured out that it was probably a combination of a bad habitat ( I was a good deal younger ) and a molt or two gone wrong. However, he's been on his own ever since, and he's about twelve now. He seems totally happy on his own -- he's active and friendly. Which is why I hesitate on adding in friends.
The LAST thing I want to do is upset the apple cart. This is not an issue of cruelty, this is an issue of me making absolutely certain that I'm doing the best thing for him and or any future tank mates. I'm a hyper cautious owner and I really just want the best for this little guy. He's my first priority here. I need to make sure he's in the best place I can offer him for now. Any and all advice is extremely appreciated, just please leave the torches and pitchforks at the door!
Although I do understand your concern because of behavior I have seen on other animal forums. 
I've used fake plants for 6 years with no issues. I also love dollar tree plants! Saves money because they do end up needing to be tossed after a while.