Will a short trip to Hakone be too rushed?

My flight is 10 AM tomorrow and I have a capsule hotel near the airport booked to rest. Our plans for Hiroshima today are cancelled because it might be too rushed, I'm considering to stop by Hakone on the way to Tokyo (We were supposed to do Hakone a few days before but cancelled the trip, since it was raining). I'm thinking of going to the Tenzan onsen, trying the black eggs and maybe ride the cable car in Hakone. Would I have enough time/would it be too rushed? Are the places close together in Hakone or is the transportation system complicated? Or should I just spend the day going around Kyoto before I head back to Tokyo? Thanks in advance