HAH< I hear you trying to find kids today willing to do manual work is not easy, even with free food or even cash, they just don't want to do manual work no more!
but was thought, never know, a COACH might be easier to bribe and MAKE the kids do it, pending who you know LOL
but honestly, you hit the nail on the head,m renting the right equipment is honestly the best option, if the cash is there, the right equipment can do a lot in less time than , the wrong gear

If your front end loader struggles to move things, a box blade ain;t going to do much better, you will again end up damaging it, and any rental fee's might be higher than renting the right machine
Maybe price an excavator with a blade on it
as again, if you can dig them to the top, you should be able to scoop them up in a bucket, a rock bucket saves the loss of a lot of top soil, thus my saying about them!

if you have a good rental shop , and there willing to work with you, you can some times get them to offer the rental by the hr on the machine
and then maybe get them to haul a tracked skid steer and a excavator LOL all for one price, and get a half day on each charge
excavator to dig em out, a rock bucket on the skid steer, to clean them up
a full day like this with two machines, should clean up a lot of rocks, and both being tracked machine, not compact things too much, or make a mess

but a lot comes down to your budget and how willing a shop is to work with you

I been lucky at times a farmer near me has a big rock picker and is a friend, so over the yrs, he's moved a lot of rocks for me
NEVER been lucky to make any money off the rocks, but I have had folks want them for free, and come and removed them from a pile I had , that was covering about an acre of tri axle loads of rocks from fields there?

e at times if you pile them so they can be had later on