Yes, if you do no sparge. No need for a bucket to catch runnings that way.
Drain the Mash tun right into the Kettle after you have drained it from it's first duty.
If you have a second cooler, you can heat your sparge while mashing and then pour it into the second cooler. Then either gravity feed into your mlt or batch sparge using a pitcher.
I set up 3 tier gravity feed fly sparge and get 82-86% eff.
You can also do a brew in a bag. Put all of your grains in a mesh bag and mash. When done, pull out the bag and boil. I just built a keggle for this purpose.