I use an excel spread sheet which can be infinitely customized ... in fact, I have changed it as I upgraded to the IO-550 and then again when I added Osborne tip tanks. The excel sheet has formulas" built in, so all you do is chage the weights and it does the rest of the math automatically. I have it loaded on my iPad together with a copy of weight & balance graph. It has worked very well for me and I only wish I could figure out a way to create the same thing for T/O & Landing as I find the tiny graphs VERY difficult to use.
If you send me an email address, or better yet, tell me how to attach a file to this post, I will send it to you or post it here.