As you said, fussy cutting is probably your best bet when you don't have a lot of it. The blocks wouldn't all need to be the same size/shape. And you could build them out with borders or even log cabin style. Another possibility would be D9P, if you can fussy cut all the same shape/size.
The possibilities are endless! Have fun and we'll look forward to seeing it.
I have a piece I've been considering doing the same with ... I've marked it with chalk a few times for the different possibilities, so that I'll get the best use and waste the least.