If you take your time and work carefully, it can be done by one person with no special tools, I R&R'd an 8ft bed on a '76 Club Cab I used to own.

BUT, that was back when I was in my 20's too.

If you don't have a hoist or lift you can use, bribe your friends with beer. A 6 or 12 pack is w-a-y cheaper than a trip to the ER.

It's really not the difficult. I would suggest removing the wheels and maybe the bumper too so the bed doesn't have to be lifted as high.