So I'm picking up a new 75g tonight for a great deal, caveat being that I have to take the three clown loaches and bumblebee catfish. I read that clown loaches can be difficult for a planted tank which is what my goal is ultimately. Does anyone have experience in this area?
I can only speak to my personal experience.
Until just recently, I have kept a small group (4) of Clown Loaches in a heavily planted tank for years. I never experienced any issues with plants. And while I don't have ground cover, I do have lots of dense groupings of different plant species, and never experienced any uprooting or anything at all.
Of course you will get a group of folks saying you can't have them in a 75G because they get too big. That is true, they do get quite large, but that is many, many years down the road, and they are very, very slow growers.
Personally I buy them when they are very small, then keep them until they get a bit over 4" or so. Takes years. Then I trade that group in and get another group of small ones. Larger (4+ inches) Clown Loaches from a wholesaler are ridiculously expensive, so the LFS is thrilled to get them. There is always somebody who is looking for larger ones, and they are a quick sale an go for a very good price.