Tomatoes take me around two to three days for 75%. Four for 100%. However, that requires a lot of AFK'ing on your farm.
You seem to agree with the OP that you can't do anything else while farming, and this is untrue. I could easily run 1-2 shadow missions in the 20-minute period, 2-3 in the 30-minute, and 4-5 in the 40-minute. Flying pet makes it easier, but it's not completely needed.
You didn't mention farming zombies either in Their Method or TNN. =|