That is another beauty of the Baxley sportchalk. You only need two straps to pull the bike forward into the chalk. Technically you do not even need them as the sportchalk will hold the bike upright without straps. They just keep the backend from bouncing around while moving.
On another note the front fork seals will not blow out if you pull them all the way down. Front fork seals only blow out from being old or from a very hard impact. (Which typically has done way more damage to the bike to worry about then the 20 dollar fork seals.)