After an unpleasant struggle using long 2x4s as levers to precariously raise the heating unit up to my greenhouse roof for installation, I bought a block&tackle/pulley. I haven't had a chance to try it yet, but I am looking forward to needing it for something.
the only reasonably priced large containers I have found (>20gal) are the fiberglass(?) ones that Costco sells for ~$30-40 in spring.