Instrumentation... Opinions?

I am planning on arranging a piece for my ensemble. Unfortunately, we have two violins, a viola, two clarinets, and a piano. Does this instrumentation not work? That's what I was told after consulting some of my other music friends. 

I don't see why it wouldn't. I have seen stranger ensembles.

Well your music friends are wrong, lol. It is a somewhat unusual combination, but I think it could work really well if you do it right.

Go on! This is great instrumentation!

Actually... I probably should have described the parts first. Sorry. I plan on arranging Tchaikovsky's Romeo and Juliet Overture for my ensemble. The strings will keep all of their parts, except for the cello and double bass, since we don't have those instruments. Then, this is where thing are a bit strange. I thought it would be cool to give the trumpet parts and solo clarinet parts and bassoon parts to the two clarinets, with the write transposition and changing some of the ranges of course. Also, the piano would take the cello, some parts of the double bass, and the rest of the instruments that aren't covered... There is a limit to how many notes my friend on the piano can play at once, so I might have to exclude some parts. What do you guys think of this?

Actually... I probably should have described the parts first. Sorry. I plan on arranging Tchaikovsky's Romeo and Juliet Overture for my ensemble. The strings will keep all of their parts, except for the cello and double bass, since we don't have those instruments. Then, this is where thing are a bit strange. I thought it would be cool to give the trumpet parts and solo clarinet parts and bassoon parts to the two clarinets, with the write transposition and changing some of the ranges of course. Also, the piano would take the cello, some parts of the double bass, and the rest of the instruments that aren't covered... There is a limit to how many notes my friend on the piano can play at once, so I might have to exclude some parts. What do you guys think of this?

You shouldn't blindly copy the parts. You should take into account the context of what the piece is saying and with what timbre can you best express it. The piano shouldn't play all of any instruments, rather it should play the most pianistic phrases.

Don't make the mistake of trying to faithfully replicate every note in the original, either. Even some professional arrangers do this and the results are never pretty. Essentially you are recomposing the piece for chamber ensemble.

Here's an arrangement of Haydn's Surprise Symphony for flute, violin, cello and pianoforte that may offer some inspiration. https://play.spotify.com/album/562hvUpua4rNfd6qLKKQeV (tracks 9-11)

Actually... I probably should have described the parts first. Sorry. I plan on arranging Tchaikovsky's Romeo and Juliet Overture for my ensemble. The strings will keep all of their parts, except for the cello and double bass, since we don't have those instruments. Then, this is where thing are a bit strange. I thought it would be cool to give the trumpet parts and solo clarinet parts and bassoon parts to the two clarinets, with the write transposition and changing some of the ranges of course. Also, the piano would take the cello, some parts of the double bass, and the rest of the instruments that aren't covered... There is a limit to how many notes my friend on the piano can play at once, so I might have to exclude some parts. What do you guys think of this?

Please don't do that, and heed U238 and Shadowwolf's advice...you are basically recomposing the piece for a slightly unusual chamber ensemble. I would advice you should study Tchaikovsky's orchestration/structure (probably the whole score) carefully and try to bring out certain nuances that you feel would best suit your ensemble.

You'll get a performance and a unique opportunity (which is hopefully inspiring) to write for that particular ensemble . What's the issue again?

The problem is that some of my other music friends say that the ensemble won't work because of the weird instrumentation. Also, I'm not really understanding, sorry. When you guys say that I should study the music and then write the music, isn't that just recreating the music for the ensemble? Should I be changing parts so that the match the instrumentation better? I didn't want to do that because I wanted to stick to the original as much as possible. 

isn't that just recreating the music for the ensemble?

Yes. That's the essence of arrangement. To make it sound as though the original piece was written for that ensemble.

Instead of working from the full orchestral score, and trying to compress it, you may find it easier to start from a piano reduction of the piece and expand it.

Its not a bad instrumentation at all. Clarinets sound good with violins, violins sound good with a viola, and they all work well with the piano. 

I think that the biggest problem you would have, is that the clarinets and the violins don't have a big range