I wouldn't encourage the use of a flexi on a husky or any dog that you're trying to walk on a loose leash, it pulls the collar and you want to stop that sensation not enourage it. (I do use a flexi but I'm not training the dog I walk, when I'm trainng I like to be totally consistent so wouldn't use a flexi for that reason)

What I'd suggest is a long line, 100ft or more if you can get one longer. Tie knots in it so that if she decides to go you can stand on it and the knots will hold, also helpful for grabbing so you don't get rope burn! You can wrap it round a tree too.

The recall on a husky is going to be a challenge! Work the recall by using the long line, when she comes back lots of praise and treats, as long as she's on that line you're in control, take it off without a strong recall and your husky might be gone. I know a few most of them don't come back, whether that's genetic or learned I don't know as it CAN be done, some people manage fine.

There's loads of threads on here on loose leash training. I like this method as it helps to build the duration of the loose leash walk, you don't have to use a clicker, a praise word works when followed with food.

"300 Peck" - A Simple Method for Increasing Duration or Distance - Part II | Karen Pryor Clickertraining

There are a load of people who take huskies out on rigs in your area, I'd ask around and get someone to show you how to do it. They use specific harnesses for pulling and your dog will work out when it's working or not, she won't think she's working on a flat collar.

I promise it can be done as my friend walks his husky on a flat collar and lead (wainwrights at PAH, they're really nice soft leather!) just fine, don't give him your tennis ball though as you're not likely to see it again!