So, since you get kobans for free, re-interpret "can I finish this F2P" as "can I finish this without spending kobans", the answer is probably "Maybe"- it depends on the champion fights
as mentioned above

start event with max fights/arena challenges
7 days, 1 fight every 30 minutes, 1 arena challenge every 30 minutes, and ignore the champions
7x24x2= 336 tokens
max fights = 356 + winnings
max arena = 351 + winnings
prizes= 35 fights

Day 1 - finish steps 1-7
Day 2-3 finish step 8 (15 remaining arena from day 1, + 25 earned of 48 from day 2)
day 3-4 finish step 10 start fight (left over from day 2)+30 (stage 4+9 prizes)+40-48 earned day 3+ 10 earned day 4)
day 4-5 finish step 11 (6am day 4- start 15 arena tickets +36 arena tickets earned by midnight+ 16 of 36 fights as PVP
day 5-6- finish step 14 (70 wins) start 20 fight 0 arena- earn 48 of each during day- should be done with 1400
so, if you can lowball enough to do 120 champion fights in under 48 hours or so, you can finish everything without Kobans

for deciding if it is worth spending kobans
15 arena fights(full refill) = 31 kobans
20 fights (full refill) = 36 kobans
rest skip (champion) = 1 Koban
Champion fight ticket = 20 kobans or 60 energy
day skip (champion) = 72 kobans
Double all prizes = 1200 kobans

prizes (purchase value)
level 7, 3 star pull- 140 kobans
level 8, girl 900 kobans (mileage may vary)
level 10, 6star pull- 330 kobans
level 13- 5 90koban pulls- 450 kobans
level 14- girl 900 kobans

all other prizes simply reduce costs, so are not important when figureing out if what you spent is worth what you are buying