Battery power source for new project. Please Help.

Hi to community.

I am newbie to arduino so please be patient.
I want to make a new project that will scale an object and have the weight in my cellphone via GSM.
I will use the scale component from SparkFun and the this gsm module (1.5mA in sleep mode ). If you can suggest me anything better i will appreciate.
The problem tha i have is simple. Power. I may use 6 type D batteries but i am not sure if they are going to last over two months.
Please Help. Thanks a lot.

Maybe something like this would help

Or something like this:

And i will charge it with the Solar panel given above right? will this stand for 1 or 2 months at least?

Thank you.

Can a 7.2 battery work with arduino?

Could something like this help me ?