I figured that at about 10 foot wide lanes gives me about 450 feet in total length. Theoretically if I can jam all that length in the L shaped box then there's no wasted space and gives me a lap length of 450 feet give or take. The real problem I see is the 30 foot part of the L which is to say that there has to be an even number of lanes in a certain leg. 30 feet is 3 lanes, but 3 lanes is impossible (down and back once or twice = 2 lanes or 4 , not 3)