I am on the other side of what they are saying....I have 3 tanks..a 90, 25, and a 12....All be operating for over 3 years now....
Now in my 25G (the closest to your question) I have 6 fish and they have been in there for over 3 years as well....A Potters Angel, Yellow Tang, Green Chromis (there were 5, but as always with schools all die but 1), an Engineer Goby, and 2 Clownfish....So I would say you would not be over loading it.... Look I had 11 in there at one time.
And I feed twice a day.....so there for the people that may ask that.
Now I do have like 30 pounds of Live rock in there, I do water changes once a month at best...have a cheapo hang on the back filter, and have a skimmer hanging there that has not skimmed in a year...It a crappy one...so it just makes noise.
So as long as they have places to hide and or host, do it.....Hell look at the fish stores with 40 on a little 10 gallon or so..Granted they are not in there for long hopefully.
Do water changes....and I think you are fine. Clownfish need no room at all..Hell mine rarely leave my frogspawn more than an inch or 2.
Also I had a big tomato clown and a false clown in the 12 gallon..They got along fine...
So make your own judgement on the clownfish rules..I don't buy into it personally.