if it's a public road and the public section in question touches it- you have legal access
if you're on private property with permission and there is an adjacent piece of public land- you have legal access; but I'd caution you that going onto someone's else's lease (state or BLM) can cause a big rift between neighbors, so I would ask the landowner whose deeded you're hunting if it's alright
we have several Block Mgt cooperators that specifically state that you are not use their private land to access a neighbor's lease (state, BLM, FS)
if you have legal access via stream access, for big hunting- you have legal access; our stream access law has several nuances that you need to be very familiar with (where is legal access, what constitutes a navigable stream, where is the high water mark, etc)
corner cross at your own risk- I think statistically the odds are in your favor here, but still far from 100%
when ever considering any of the above, insure you know exactly where you are- if you access a chunk of public and there isn't legal access, you'll very likely pay the price
good luck with your antelope hunt!