Leadscrew position, help!

[kong]

Take a look at the photo, you will have to imagine the block in the middle (name?) is on bearings, and slides on the steel bars across the gantry. So the question is what is the best place for the leadscrew? The problem is, i have only 16mm gap on the insides of that sliding block, so I will need to use 1/4" screw if it is to be inside. Ideally, I would like to put it on the bottom of the block, where I can use a 10mm screw, which I have already (I say leadscrew, but it is really threaded rod). I'm just worried about excess pressures on the screw if it is in different areas. I hope you know what I mean

[HomeCNC]

Put the lead screw on the back of the plate with bearing flanges mounted to the Gantry. Place a nut flange on the back of the slide to mount the nut on.

[kong]

My poor design I'm affraid! The cross rail is mounted at the very back of the gantry, so no room on each side to mount the screw bearings, unless I make two new pieces and bolt them on each side of the gantry. Is this still the best option?

[kong]

Some more thinking later...
I thought of routing a channel across the centre of that cross rail, that way the screw/nut can be mounted on the inside front of the sliding block, saving me from making mounting plates to bolt on the top/back of the gantry. Thanks for the help, any other pointers greatly appreciated!