I've used this arrangement many times over the years to move my old 800 pound
engine out of the
engine compartment, so your
dinghy should be no problem. As the other posts suggest, use the halyard to back up the topping lift, and use a couple of tag lines to control swing. I use my
boom vang, which is a 6 part block and tackle, rather than the main sheet, to do the lifting, just because it is easier to remove and replace than disconnecting the main sheet.