Don't understand how you can have a "BMX cruiser"
BMXes are built for short bursts of high intensity riding, while cruisers are built for - well, cruising.

And unless you switch to a SS f/w and redish the rear wheel, your bike won't get any stronger.

It's a lot of work only to be able to remove chainrings and derailers.

You might as well ride it as is and see if it survives.