He can not taper or go thinner with the airfoil.
The rules are pretty clear.
48" constand chord, minimum 1 3/16" thick at the high point.
Maximum wing length 52", minimum 500 square inches.
To me, I've always thought that the optimum tip would be 52" at the trailing edge and 48 " at the LE and whatever chord width it takes to give you 500 squares. Then taper the tip as sharp as possible outside of the 48".
Except that the above is wrong. Constant chord and 1 3/16" thick for
47 1/2". Yeh, it's a small point, but that extra 1/4" does help when shaping a tip.
Hoerner wing tips provide the largest effective span for a given geometric span or a given wing weight.
Was that printed on the back cover of Hoerner's book? Because I'm not buying it.
Edited for spelling error.