Do it a few times in a week and it gets real easy ! I did an (1) out, in, (2) out in and an (3) out in all in a week while I was "checking" used transmissions. I'm 65, and I did it myself. Yes, LONG extensions expose the top bolts once the rear of the trans is lowered a bit.
I used to do them with a floor jack, but I tell you, my buddies Trans Jack (like in link below) made it much, much easier. If you can find or rent one rather than using a floor jack, do so ! Jack the truck up as high as you can get it right off the bat. Use good jackstands !
Don't forget to have a small hydraulic jack and some blocks to put under the oil pan so the engine doesn't hang back on the firewall, and it also helps for quick realignment on reinstall. Too, for reinstall, it can be helpful to put a longer stud in the midway holes for alignment that you can see better. Once slid in, get the top and bottom bolts pulled up, remove the studs and put in those two bolts.
Make double sure your torque converter is pushed into the tranny proper before pulling that tranny up to the belhousing. And, watch your wiring harness over the top so that doesn't get pinched. It's hard to see in there so look closely.