It's a standard mod. I will let others more knowledgeable than I comment on the chassis rigidity, although the crossmember is a pretty stout piece of steel, and even while removable - it gets bolted quite solidly between the frame rails.
IIRC - IPSCO sells a nice one, as I am sure to many of our vendors.
Nevertheless, we just cut mine out, and then welded flats to each end, and grinding any irregularities off the frame.
OBTW: If you are doing this for access to the oil pan - you have to do the handbrake as well.
And guess how many times I have used the removable brackets after we installed them?
Bracket Removals: 0
Engine Pulls: 3