wood filling question

I cut some 2x4s to make a frame that will under the floor for reinforcement.
It will not be going on a trailer but will be a slide one or drop in unit.
The Lap joints that I made I cut on a old over head saw that had an unevern cutting board. So my joints now glued are rought gappy and uneven.
My question is this will not be seen normally what should I fill these joint in with? Galking, polyglue that foams, wood putty, plasic rap??
My conserns are more water getting in the joints or insects. I have heard some folks stalk about coating the total bottom with a substance too.
Ron D.
It will not be going on a trailer but will be a slide one or drop in unit.
The Lap joints that I made I cut on a old over head saw that had an unevern cutting board. So my joints now glued are rought gappy and uneven.
My question is this will not be seen normally what should I fill these joint in with? Galking, polyglue that foams, wood putty, plasic rap??
My conserns are more water getting in the joints or insects. I have heard some folks stalk about coating the total bottom with a substance too.
Ron D.