Get some extensions it's worth it. Moving the skid back 4 " will put you out of your support plates so you'd have to move them plus it will make the front end VERY heavy.
I just got some from HOLZ for like $45 they are pretty simple and real inexpensive and have offset built in for 7.5" wheels. Durability wise I like the Tracks USA ones better but the skid already had the HOLZ bigwheel kit on it in which you cut the top of the stock axle flanges off.