I have 4 kegs (snug) on the floor of my 7 cu ft chest freezer, with the 5lb CO2 bottle inside on the hump. I tried putting a keg on the hump with a 2 x 6 collar and it just misses with the QD on. A 2 x 8 collar will allow me to put 2 more on the hump if I move the tank outside.
Also, Home Depot will routinely have the 7 cu ft chest freezer on sale for $168.00 with free shipping if you can wait. If not, check at the local post office for the moving kits, as there are usually some 10% off coupons in there for HD or Lowes. ( Save a bunch on my John Deere lawn tractor using one of those ).
Edit: My kegs are all Ball Lock