https://forums.ea.com/en/the-simpsons-tapped-out/discussion/224629/moes-ark-event-calendar/p1
This is a link to the event calendar that @LPNintendoITA has created to help players see how much event currency they need each day to acquire all the prize items. How new a player are you @Tomlovesnoodles ? There are 18 (I think) Springfielders you can use for the tasks plus the characters that can be unlocked on the prizetrack, but if you haven't unlocked the characters in the main story quest line yet you wouldn't be able to use them. Premium characters really help if you have the donuts to buy them as most of them have 8 or 12 hour tasks and pay double the standard rate (but yoyo only has 4 hour tasks). Do you have 10 neighbours to visit to get the extra currency? Invasive tadpoles help as you say, not just your neighbours dropping them in your town but you dropping them in friends towns too. Hope this helps :)