That’s certainly an option but the buses are excellent on the island, you won’t have to wait long and you can always kill time at the pub which is in a nice location opposite a church.
I’ve been thinking on your request for more walks. One would be to get the open top bus to the very end at Needles Old Battery. Let the bus turn around and go back and then follow it back along the cliff top road to the Needles Park. It’s less than a mile along a narrow road. Generally it’s slightly downhill. Only the buses and the National Trust are allowed to drive it - I’ve walked a few times and never been passed by a vehicle. At the Needles Park you can pick up the Open top bus or just a normal number 7 back to Yarmouth.
Another local possibility is bus to Totland then walk from Totland Bay to Colwell Bay (the bus is just a few minutes walk inland from there). I would check locally on that though as I’ve been when that has been blocked at the headland between the bays.
Going further it may be worth contacting Forestry England about access in Parkhurst Forest. If at least some of the paths are dry and even that may be a possibility.