Depending on the height of the trailer, etc. it is certainly possible to unload a generator in the MEP-003a size range without any type of lift. I along with a couple of helpers have successfully unloaded a 30KW generator weighing in around 1650 pounds off a standard small utility trailer with only a couple of cable hoists, scrap iron pipes, tie down straps and some 2x10's.
Jack up generator, put pipes under it and roll it to the back of the trailer
Use 2x10s to built ramps on either side of the generator (4x6 would have been better as the 2x did sag)
connect cargo strap to front of generator and around one of the trailer front braces and out to the side tied off to another vehicle to slow the lowering process and prevent a runaway situation
roll generator part way off back of trailer and place pipe on the ramps under it.
slowly pull generator off trailer with cable hoists while maintaining tension to slow descent.
roll into final position on pipes.
Ike
p.s. remember be safe, and take your time you don't want to drop one of these on anyone
also another option for mobility is one of those cheap folding trailer kits that harbor freight sells