Upgrade options for 1st mirror base

Fed up with alignment issues today, went out to realign everything only to remember my 1st mirror base, which is this:

Only today did i learn that this is K40 standard fare. It doesnt belong on 900x600 machine. The whole tower is flexy. I dont like it one bit.

Are there any good options on upgrading ? Problem is hole drilling, pretty cramped compartment. Any suggestions on what base to get and how to fit ?

I don’t want to be so scared with this construction, just the bolts are tight well. Maybe I would go up a step with bolt dimension….
If the base plate is very thin and flexible, I will make 2 aluminum plates as reinforcement but then you also need to make a new bridge.
But as I said, since there are no moving parts, I will not change too much.