So I picked up a 10'6" rod to use as a heavy float and big water spoon rod. The rod is great for my needs except the rear handle is like an inch or 2 short, so it don't tuck under my forearm like I like. I was thinking of taking it to a shop and having a certified pro style fighting butt put on it to get that little bit of extra length although I'm open to any other ideas. You guys have a suggestion or two?

that butt is more of a counter weight... and if yours feels a little short, it may even help more than with just a little extra length, id do it... i like my rods that have them...

A driftrod butt section is about 14".
10'-6" rods can be tip heavy.
If you have the work done, tell them to leave the butt cap un-glued.
That way you can experiment with adding weight (lead) to help balance the rod.
Do it fully rigged, then glue in the lead and butt cap.

I just did the exact same thing with an Edge rod I bought. Its a straight 12" carbon fiber handle with a normal butt cap and it felt too short and like there was nothing to hold onto when I swung it back to cast.

Called Batson and had them ship me a piece of scrap blank to put in the butt to extend it along with the cert. pro fighting butt style you mentioned. Removed the butt cap, epoxied the scrap blank in the bank to add another inch and a half and then glued on the butt cap. It gave me better grip, added length to the handle, and helped balance out the 11'3" rod a bit better with the counter weight. Made a near perfect rod into a perfect rod! I think you're right on with that idea.

A simple fix is to order a weighted butt cap that just slides over your butt cap.

We've done some custom counterbalances with pencil lead pieces fastened with epoxy and masking tape but you have to sand it to fit into the blank. Other rods I've bought brass that screws into the butt handle. Even had Batson put a counterweight on one of my rods.

The rod isn't really all tip heavy. I've got a 1st gen revo inshore on it and it balances right around the center of the fore grip with a 1/2 spoon tied on. Since it sounds like I was on the right track with the fighting butt, I'm gonna drop it off next week and get it done. The extra weight from that should move the balance point back close to the reel.

What I've done with tip heavy rods in the past is notch out the cork just above the butt cap to put a wrap of pencil lead around it and the wrapped the the handle whatever after market grip wrap I saw (I think it x flock or something like that). That was just easier than any of the other options I found to counterbalance a rod.