Made a new pan last year make sure you take into account the Y axis carriages If you make it much deeper the pan will interfere with them. 2.450 is the deepest you can go without re engineeering the table. I welded 4 tabs on the bottom to secure it to the chassis. This way you won’t need to drill holes in it to secure it.
I agree with everything you said and think this is the way to go.
Only replying because I tried to do this and STILL got a leak. I am very much a TIG amateur. I am pretty sure the leak came from a gap in one of the troughs that are cut for the bolts. I had difficulty getting in there without sticking my electrode.
I would recommend to anyone who is not so confident in their TIG skills, take a cutoff and open up those troughs a bit for better electrode access.