Yes - you could use a composite flight plan in the scenario that you are asking about. Composite flight plans have many other uses just VFR-on-top. My community in the military used them often for an IFR leg to the start of a VR low level route, then to pop off the VR and pickup IFR handling again for the trip home.

Since you are a new IFR pilot, I encourage you to fly in the IFR system as much as possible (to answer one poster who asked why would you file IFR in any case) and to try as many different techniques as possible as have been suggested to learn to how work the system to it's greatest advantage in your favor. Ideally, it would be the best to work all of these different techniques in the safety of actual VMC conditions before venturing into hard IMC - think of them as training runs - but file and fly as you are comfortable with when you have no choce but to fly in true IMC conditions.

I took a IMC cross-country just 1 month after getting my instrument ticket and only one VMC flight inbetween. Probably not the smartest thing to do, but it was some real experience right out of the bucket. Just be careful and don't overestimate your abilities and get yourself into a pickle.

Have fun!

USMCFLYR