No worries. Just go faster. If your strength is fading during any part of HST, just go with the partials for awhile. You'll get the same net effect with strain-induced hypertrophy.
Usually, I'd go with adding stretch-point movements to speed up arms growth. But for the sake of simplicity, you may want to add in some of the DC/fascia stretches targeted for the arms. Add these during 5s.
cheers,
Jules