Chosing between tanks& bully crabs?

[Krisrath11]

Ok so here's the deal I have my hermies a tank I got that is a 40 gallon breeder. The ecuadorians are moving to the new place and the others (PP) are staying (hopefully they're alive I haven't seen them since they have been home). Question I have is this...

I have a leopard gecko who never utilizes his 75 gallon tank he definitely doesn't need the space but the dimensions are 48x12x20 the other is 36x16x18. One gives more floor space while the other more surface area. The gecko can really do either but there's more floor space in the 40 but more actual area in the 75. My gecko really hasn't done much for climbing since he's been here really (years or so I would say, he's about 6years now from what the lady said) so the loss of height is not a concern there. The hermits seem to at this point enjoy the climbing more than anything but would it be to narrow? I want to do what's more beneficial to them since he'll see it as an upgrade of floor space. I was going to try to setup today but while I was just looking at Leo's tank I was wondering if I was a better option perhaps?

I also have a question of do they sometimes just not like one of their cage mates?! So the e's came from the same place I am almost positive that's what they are they're definitely not pp like the poor bad condition ones (box store but definitely not what is normal even for one of those) but they (other e's) seem to almost pick on lighthouse (they came with painted shells that's y the name). He sits in their spot he gets literally shoved out I thought they were having a shell fight but nope it was basketball and I believe his girlfriend green cat shoving him off the vine, they shove him out of the saltwater bowl, just picking on him really I think. Is that a thing?! Basketball is the biggest, lighthouse is slightly bigger than cat almost the same though. Do I need to separate them and just set up and find someone smaller than him to room with? I'm genuinely concerned I'll find him spread all over the tank one day cause they decided they wanted him gone for good. I've got at least 2 extra 20 gallons at least 1 is a breeder so do I need to separate and find a smaller companion he might get along with? Is this just them working it out? The 2 are now at the top of the tank stuck to the lid so he's meandering alone awhile and seems lost and like he's looking for someone so I just feel bad for him getting picked on them being alone. Maybe I am overreacting but never hurts to ask as opposed to him being dead later because I didn't.
I don't want to leave him with the pp either cause they seem like they've had enough trauma for a lifetime after their store conditions I'm hoping they'll all surface at any point so they get to stay separate and it'll be easier to see if anyone is actually alive because then I'll know it was them if something is moved or anything is disturbed (no smell yet so I have high hopes for the little ones).

Thanks y'all for the help