So my plan is to drill the bottomside of the tank and use a single piece of pvc as an overflow. Anyone hear of pvc glue being bad for tanks? Just a hloe at the bottom with 2 in pvc running to the top of the tank

That is similar to the old perfecto overflo design. It went away for a reason. You will need a strainer at the top and that strainer is very important and easily blocked or clogged, hence the tank overflows.

I have used pvc glue many many times with no ill effects

It is set up justlike a normal overflow a 90 elbow through the back of the tank with a pipe that runs to the top. The 90 will go through the back of the tank somewhere, top bottom????? and plumb to the sump.... I can cut teeth in the pvc, it just is a pain, I may just use egg crate. Adlustments is my problem though, thread fit with teflon to adjust up and down? Or vinyl tubing on the end? I can;t cut it when its wet, and I can't smack an extension on it when the bulk head is on the tank. One shot deal without adjustments or add an extension to it? Any thoughts?

If I were you what I would do is put a 90 on the bulkhead with a threaded end. If you do that then it's not a one shot deal, you can put a threaded adapter on your stand pipe and put it in and remove it as many times as you want. If you set it up the first time and it's too tall, just unscrew it, cut some off the top and screw it back in. Or if you come up with a different design for your stand pipe then it would be easy to change. Of course you will want to make sure to put a ball valve on the outside right after your bulkhead so you can shut off the flow while working on it so you don't drain the tank, but I'm sure you were going to do that anyway.

Yeah I have ball, one way ceck, and quick disconnects for the return and ball and quick disconnect on the into sump. The problem with that is is thaat i've always had a hard time finding threaded fittings that fot bulk heads. I ust did a tank for a guy and he got a CPR overflow, but the threads were like 1 5/8 and nothing at lowes or HD would fit. I ended up turning the bulk heads backwards and gluing the down pipe in to the overflow. Any hints on bulk heads that have normal threaded dimensions? Any one use the Drs Foster Smith ones? Thanks!

I have bought all of mine from marine depot and BRS, never had any problems with threads