orchestration Orchestrating Eine Kleine Nachtmusik, How to go from String Quartet to Orchestra

So, I just got this idea yesterday of orchestrating Eine Kleine Nachtmusik. Should be easier to do than the Pathetique Sonata orchestration I did before. Since it is Mozart that I am orchestrating, I'm staying conservative with my instrumentation. Here is the instrumentation I plan on using for my orchestration:

• 2 flutes
• 2 oboes
• 2 clarinets
• 2 bassoons
• 3 horns
• 2 trumpets
• tympani
• 1st violins
• 2nd violins
• violas
• cellos
• double basses

The reason I haven't put in numbers for the string instruments is because most likely, the orchestra will decide on their own what the best strings:other players ratio is or will know it from playing Mozart symphonies hundreds of times. Either way, it isn't like I know the strings:other players ratio for a classical period orchestra(which is what I'm aiming for with my instrumentation if you can't already tell), so I would have no clue on the ideal numbers for the string instruments.

There are some spots where I see Mozart writes a phrase and then he repeats the phrase. These would be prime times to bring in more players or have some players take a rest(really depends on the dynamics of the initial phrase and the repeated phrase). And there are some extended creschendo passages as well. Those would be places where I increase the sound density. Extended diminuendo passages, I would do the exact opposite for. I would decrease the sound density.

But do you have any suggestions on how to go from string quartet to orchestra? And in particular, what should I do about the triple stops that start the piece? I have been told that double stops, while they sound great in a solo, or even a quartet, when you get to the size of an orchestra, it becomes clunky in sound. The double stops I can simply either have more than 1 instrument group play it or make 1 staff divisi. But I have no idea what to do about the triple stops. If double stops sound clunky in an orchestra, then triple stops will sound even more clunky in an orchestra, so I obviously can't just leave them as triple stops. But what should I do about those triple stops? Here is a PDF of the entire piece as originally written:

It shouldn’t be difficult except to keep the piece light. The harmony and vertical chordal structures are well laid out by Mr M. All orchestration need do is reinforce the sound as needed, or swap out string phrases for winds to change timbre. There’s scope for antiphonal phrases like measures 1 and 2 against 3 and 4.  

No worry about those “triple” stops. They’re just arpeggiated chords to get a fullness of sound on the first note. An accented down bow I'd guess giving an incisive sound. You can replicate the effect any way you want.  The opening phrase would be detaché anyway but it’s up to you to interpret how Mozart would expect it to be articulated – one of the challenges.  You could lay the opening chord out as double stops for all string instruments. They shouldn’t sound clunky. From m5 he wrote many double stops, light and staccato. The opening cello could play G & D together, likewise the viola, the violins unison B and G. Or swap out the string double stops or arpeggiation for winds. Could be woodwind or brass. Depending on your style that first chord alone could be reinforced followed by something lighter. 

I won't comment on your choice of instruments as you'll discover what you need as you progress.

Good luck.