you could try to fill them with mesh tape and joint compound then sand ,but many here and myself have tried and had poor results,over time cracks begin in the seams. mobile homes move and flex because of the way they're constructed. like a big box on a flat bed trailer. the spaces between the panels allow for this movement.the strips on the seam cover it to give it finished look. depending on the size of the area filling them may work ,but i wood maybe replace the strips with a finished wood moulding . in my home i used 3/4 flat moulding with a pattern stamped in it , works for what we where trying to do, just a thought.we stained to match the baseboard and window moulding i made.or you can just paint the wall color, or a contrast color. look in past posts there are more suggestions and types of matrials ,used by are members.
"a man has got to know his limitations", clint eastwood. " i haven't found mine yet," me