Lake eildon: mountaineer creek with kids

Hi, I would really appreciate some help planning a walk I've seen mentioned on this forum. We would like to do the blowhard spur walk, camping overnight and then returning via the lake shore, with our 3 kids, aged 9,7 and 6. They've done overnight hikes a few times, mainly at the prom. We will have to do it over 2 days, in a couple of weeks. I've seen this walk described as ' hard ' and have not been able to get an idea of elevation change or actual distances. Could I get some information about the length and difficulty of this walk, including what the track is like, is it well marked/ difficult walking?
Thank you in advance!
Thank you in advance!