I tried 'over'... as in, I see you over the wall (which makes sense in English), but duolingo reported as wrong. However, I believe através also means over: ( https://translate.google.ca/m/translate#pt/en/através ). Do not click the link. copy and paste it.
Hm, seeing conflicting info on this one. Acceptability of "thru" seems context-dependent according to various sources, mainly used in technical writing, and not used in UK. More generally acceptable than "tonite" for "tonight", less than "donut" for "doughnut". Personally I tend to avoid it.