HCA: Hermit Crab Association

I know that tall tanks support less crabs, so I would assume a long tank but most of the long tanks I have found are not very tall and I have no places to put climbing toys. I currently have a cube shaped tank that works pretty well, but would it be more cramped for the crabs than if I had a longer one? the one I have is 18 inches tall and filled with 6-7 inches of sand, meaning I have about 12 inches of tank upwards for climbing in a cube. I was thinking about changing it to a 30ish gallon long, but then I would only have about 8 inches of tank above the sand. I am leaning towards keeping my 25 gallon, but a bigger tank would be helpful...
any suggestions would be appreciated, thank you!

What is the 'foot print' of each tank? Like how long and how wide?

14h, 18w, 30l. Its a bit larger than 30 gallons but similar.

My current one is 18l 18w 18h