I have a 1986 BJ70 and have done month long trips and never worried about it. I drove from Boulder, CO through Utah, across Nevada, over to the central coast of CA up to Tahoe, up Eastern Oregon, through Idaho, into Wyoming and back down northern CO this summer.
A month before that from Boulder, to Flagstaff, AZ to NM down to El Paso through Big Bend, over to San Antonio and Austin, then across LA, up MS, across TN, into AR, OK, the panhandle of TX, back through NM and then up Southern CO.
I drove from Boulder to Asheville, NC and back last fall. I just drove from Boulder to Central Texas, and frequently drive from CO to CA. I have plans to drive to Prudhoe Bay, AK starting in May.
My point being you shouldn’t have any issues! Be happy cruising at 55mph, get a seat cushion and you’re golden.
I agree with doing an oil and filter change before you go and maybe a fuel filter too if you haven’t done that in a while.