here's the deal. i have a 1542 tracker riveted boat,15" transom, with a 23hp godevil.
the boat is great for what i use it for but i need more room in the boat.

wish i could buy a new/used mud boat hull but that is just a dream for me right now.

So, i want to remove both bench seats and install an 1/8 aluminum floor(got sheets for free).
I know with the benches removed that i will need to add support so boat will not twist.

Was thinking of adding 1 -1 1/4 aluminum tubing right underneath gunnel,full length of boat, basicly making a double gunnel.

would this be enough support/bracing?
any help would be appreciated.

While it'll definitely help, you're probably still gonna need more.

I did this same mod to my boat, pulled all the seats out and put an apuminum floor in. One thing that matters most, is your seat connected to the floor, or is it just sitting on it? My seats were only riveted to the sides, gravity did the rest. This told me that they weren't doing anything but hanging there, so I tore them out and it didn't change the flex at all, my boat has zero flex if you grab the bow and try to twist it.

the seats are riveted to the floor and the bracing on the sides do not go all the way up to the gunnel, only halfway.

When I pulled my middle seat I put a brace in using 1" aluminum angle and made a brace. I had access to a welding machine and was able to weld it in but I'm sure you could get away with rivets or stainless nuts and bolts. I just ran it across the floor like the rest of the braces and have no problem with flexing

Well, I would get in front of your boat, grab the bow with both hands by the gunnels and see if you can twist and flex your boat. Then take your seats out and see how much it changed it. If it makes it flimsy, add back some braces like you see in my hull, maybe 1 or 2 in place of each seat you take out.