Having done both, my vote is solidly for August over spring. With spring hunting it's as if you're too early or too late. As a nonlocal, you're definitely hitting it right time wise with August. Though if you were around for an extended time in May, that may be the way to do spring.
While transporter hunt prices are skyrocketing, if you're looking for more of a success than a learning experience, it's a better option than going off the road...again from personal experience of doing both as a nonresident. Though being there throughout the month might, again, put some odds in your favor hunting off the road system as a novice especially if you find a local friend. In Alaska, the road and trail system are way more limited than they are around the Rocky states (again, having done both) and much of the bush and slopes basically impossible to traverse.
That said, it you're working without much time off, the road might be your option. Keep in mind aircraft require good weather to fly and you shouldn't be surprised if your departure and return end up being on mother nature's schedule instead of yours.
Good luck to you whatever you decide. But having done it several times, I recommend you heed the constraints of a nonlocal even being there a month. Even the transporters will treat you completely differently than a resident. They can have the last word if they want, but that's the way it is.