Work on the stuffing box while the boat is in the water
I think the friction fit of the hose on the tube will be enough to keep most of the water out. You only need to loosen the clamp and move the hose a 1/2" right ?! I wouldn''t worry. If you -really- concerned I have heard putting some plumbers putty on the outside around the shaft is a good temporary fix for water ingress.
ps....make sure your bilge pump works well..;-)