Oh what a FUN quilt this will be!!
Blue and yellow ... to keep with your blue truck theme and yellow for the sky!
Or Blue and green ... blue truck and green grass!
Or could do a mix of colours, keeping the blue as the constant.
Binding ... finish off with the blue constant.
I really like the print ... but not seeing it IRL, just want to remind you to check that the print is small enough that it will show nicely in the blocks. If it is two large, you'd totally lose it, unless, you do some fussy cutting ... but that's a whole pile more work!
Good Luck ... Look forward to seeing the finale!