if your deck does not sit any higher than the bench seats you should be fine. when i did my front deck i just layed a piece of plywood across the top of what was already there for the front seat. and then i just framed it back a little, leveled it out, and it's pretty stable at that height. my boat is a 1436 jon, and im 6' tall 165 lbs, and my dad who always comes out on the boat with me is 6' 150 lbs, and with the two of us both standing up in the boat at the same time, i on the front deck, my dad in the back of the boat, niether of us had the slightest feeling that it was unstable.
see my post for better details. trophybass.
https://www.tinboats.net/forum/viewtopic.php?f=21&t=17916