Wheel pants are always an option. On rough fields they don't last very long so many don't install them. Typically they weigh in around 4 ounces for the pair but the weight is close enough to the c/g not to have much of an impact.

50cc battery set ups are real easy. Many like to "over indulge" and throw extra money and parts at the system thinking it will make it safer or better. One 2,500 M1-A123 with one switch will handle all the power needed and more. I can understand where someone wants redundancy with a second battery and switch. In that case a pair of smaller A-123 batteries and 2 switches works just fine. With any 50cc plane it will be a very rare day to pull more than 3 or 4 amps. Hitting 4 amps would mean the servo linkages were binding up somewhere. Use an amp meter, not your ears, when setting up digital servos. Know what is happening with flight controls, don't guess.

Ignition power works very well and reliably using nicd, nimh, or eneloop AA battery packs. 1,000 mAh is all you need for a full day of flying with a single cylinder engine. Cheap, simple, no concerns about regulating. 4.8 or 6v is dependant on the ignition type. To date I have not had an ignition that did not work well using a well charged 4.8v battery in good condition, but some have reported that their ignitions won't work on less than 6v. I don't know what to say about that.

Keep it simple and keep it light. The combination will provide a great flying plane with plenty of juice to keep it in the air. It will significantly lower cost and complexity .