You do need some different kinds of fish for the loaches.
When my 5 were smaller I had them with a dozen Tiger Barbs in a 33 long. They were great togeather but I got tired of the barbs constant chasing and spawining. After the loaches got too big for the 33 I put them in a 65 gal. 6 foot tank. They are now in the company of 2 dozen rasboras and 6 Gold Gouramis. In 5 years I have never had the loaches go after any of the other fish. They pretty much ignore them.
The biggest one is about 8" too.
So, go for it. Get some fish for the other layers of the tank and have at least 4-5 loaches. The more the better. They love each others company.