The sunbeam mixers with the dough hooks should work great for mixing the meatball mixture up.
lighter & cheaper than the kitchen aid.

quite a few in the thrift stores around here for 12 bucks or so depending on condition. and you can still buy bowls, dough hooks & beaters online for them if you need to.

The plastic zip bag is a good idea too, just put it all in there close it up and mush it together - or have Alan squeeze the bag for you to get it mixed.
The gallon size might work best.

If you use a freezer type bag you could do an extra large amount - use what you need for a meal and keep the extra in the freezer til next time.