Logistic to Lake Shikotsu Ice Festival

Hi all. I would like to go Lake Shikotsu Ice Festival and stay for the fireworks on 7 Feb 2015. My flight is at New Chitose Airport on 8 Feb 2015 11am. I would like to ask suggestions/advise on how to go about this without renting a car (as I am afraid driving in winter conditions). My choice would be to stay at one of the hotel at lake shikotsu or near Tomakomai JR station.

I have looked at the bus schedule and found that the last bus depart on 1745 from Lake shikotsu - which means I would miss the fireworks if I stay at Tomakomai (unless if there are other buses that departs post fireworks). However if I stay at Lake Shikotsu - the bus only departs earliest at 951am. I would need to take a cab/taxi to the airport to catch that 11am flight (Wished I had bought the later flight - sigh). I was told taxi fare is around 5k yen from Lake Shikotsu to airport (40 min - really?) Hence I hope anyone can help me to plan my Lake Shikotsu excursion trip. Thank you

1. During the Festival, the bus will be operated by a special schedule. The last bus departs Lake Shikotsu at 19:10 and arrives at Shin-chitose airport at 20:02. This special bus will be operated on Saturday, Sunday, and National Holiday including 7th Feb. The Firework will be 18:30-18:45.
http://www.chuo-bus.co.jp/%E6%96%B0%E5%8D%83%E6%AD%B3%E7%A9%BA%E6%B8%A...

2. TAXI fron Lake Shikotsu to Shin-chitose Airport takes 60min, 12000yen. Calculated by TAXI company's website.

3. How about using bus tour? It depart Sapporo at 15:10, return to Sapporo at 21:05.
http://teikan.chuo-bus.co.jp/en/course/578

Good luck!