If you were to pull the boat completely empty, with just the outboard on, it would be relatively easy, assuming the short journey, from the garage to the beach is on the level!
You will be suprised how much more difficult it is, when you add the fuel tank, and all the rest of the kit.
I've pulled my SIB a couple of hundred metres, without too much difficulty. It helps tremendously, if you have a good set of transom wheels that are inflated to the correct preasure.
I hope this helps in your decision making!