advantage to kickoff out of bounds, am i missing something here?

[bniu]

okay, so in HS, the normal kickoff line is a team's own 40 yard line...

let's say we're in TX and playing under college rules (with some modifications like the 40 yd line for kickoffs)

I think they no longer do the 5 yd penalty for kickoff out of bounds, it's just straight up 30 yds from the spot of the kick now...

now after the last scoring play (PAT) the defense commits two a dead ball unsportsmanlike conduct penalty that will be enforced on the kickoff, so now the team that just scored (now the kicking team) is kicking off from the receiving team's 45 yard line...

if a kickoff out of bounds is 30 yds from the spot of the kick (assuming the kickoff went further than 30 yds) wouldn't it be more advantageous to aim the kickoff out of bounds at like say the 10 yd line rather than just kicking it through the end zone for a touchback? If the 30 yds is enforced from the spot of the kick then wouldn't the receiving team have to take the ball at the 15 yd line then?

What if the kickoff was from the receiving team's 30 yd line? (possible from two dead ball 15 yarder penalties on the receiving team b4 the kickoff)

most coaches i've spoken to about the rule say the ball is placed on the 40 yd line no matter what but I believe they're mistaken since they've been either watching too much NFL/college or don't really know what the rule is...and coaches aren't really known for knowing the rule book in depth...

i know this play doesn't come up too often (probably as rare as a 4th out appeal in baseball/softball) but it's the one play that I can't seem to get a clear answer from...