any recommendations for car hire in either Nagano or Myoko? after a 8 seater for 10 days
There are car hire places at the shinkansen stations. So you are looking at Nagano, Iiyama or Joetsu. Joetsu is the easiset and maybe shortest to Akakura , which is where I assume you mean by Myoko. Look at tocoo. But I googled car hire in Niigata a while ago and got another website that gave good deals. Cannot remember who it was but it was not Tocoo. It was for pick up from Niigata airport but also gave shinkansen stations as options.
book 4wd but as many have learnt booking, even way in advance, does not mean you will get. Be prepared to buy chains. Unless you are going on really remote roads or traveling in the wee hours that will be fine. We had someone unable to get to Madarao via Tangram in a 4wd but it was at midnight in a blizzard. They got through at 7am the next morning, after the roads had been cleared.