twoside really doesn't affect very much. It gives the oportunity to have different margins and headers on odd and even pages, and is detected by
\cleardoublepage but that is about it.
Your comment about "layout molesting, stuff " isn't very specific but I infer that you want the margins, and perhaps the headings to be the same, so you can put this in the preamble, which just restores the oneside settings from report class.
\ifnum \c@secnumdepth >\m@ne
\@chapapp\ \thechapter. \ %