Really? Looted wagons are a no. Just dont do it. Trukks are much better, have a gun included, and cost the same. Looted wagons are only for if you cant figure out a way to get a trukk, and even then, consider a battle wagon.
RPJ is questionably useful, I dont know that the extra inch is worth the five points- think about it, when have you ever needed one inch? On one trukk it isnt such a big deal, but when you field 6-8 vehicles we are talking 30-40 points, esp when your goal is to get to the enemy in the second turn.
RPJ will get you in combat first turn in
DOW, but even then it is questionably worth it.
Shoota boyz have a purpose, even against guard. Never just dont take them, considder if they have a role then decide. I use my shoota boyz to soften up large squads before I charge with another squad, to take out smaller, less combat ready squads, also to keep my
KFF mek covered.