Well, it'd probably be helpful if you had a full Boehm clarinet. You'd have a low Eb key. That's a serviceable middle Bb.
This chart has some of the side/trill key fingerings and that might help, but I don't think you necessarily need the alternate fingerings.
I would recommend ...
a) Memorize it. It's a lot easier to memorize it than think, "A, D, A, D," when you get to the phrase.
b) That you try a method I learned 35+ years ago (yes, I'm the Highlander): play the A as long as you want, then play the D
as quickly as possible, then play the A, etc. After you've done this for a few measures, reverse it: play the A
as quickly as possible, then play the A as long as you want, etc. So:
Long as you want, as quickly as possible, long as you want, etc. Then ...
Quickly as possible, long as you want, quickly as possible, etc.
When you've done this a couple times, try playing the phrase in time. I've astounded a couple people with the results. I don't remember which of my teachers taught me this trick, but I thank them all. Note that you shouldn't try to do this method with the entire page/piece at once. Just a few measures at a time.
I don't pretend to be a pro clarinet player and it's been a loooooong time since I played clarinet.