All of my trailers (6 of them) have the landing gear mounted about 10 in. back from the front +/- 1/2 inch.
This is pretty much standard distance to clear tandem axle tractor frames while turning.
13 in. sounds like too far back, but that depends on overall length of trailer.
This trailer has landing gear 9.5 in. back, on a 19 in OAL trailer.
It just barely stands by itself unhooked from a tractor without falling on it's face;
