It could be reasonable to collect some past examples of such proxies. This would help in assessing whether something like this is technically feasible. Also I assume that if something like this is implemented at some point, we'll need to prepare list of regular expressions for such automatic rewrites - so it is good which proxies we are concerned with. (The post is CW, feel free to add more examples.)
proxy.library.adelaide.edu.au; only 1 occurrenceproxy2.lib.umanitoba.ca; only 1 occurrenceezproxy.cul.columbia.edu; only 1 ocurrenceproxy.library.cornell.edu; only 1 occurrenceccny-proxy1.libr.ccny.cuny.edu; only 1 occurrenceezproxy.fau.edu; only 1 occurrenceezp-prod1.hul.harvard.edu; only 1 occurrencelibproxy.mit.edu; in total 4 occurrencesproxy.library.nd.edu; only 1 occurrenceezproxy.library.nyu.edu; only 1 occurrenceezproxy.lib.ou.edu; 2 occurrencesezproxy.lib.purdue.edu; only 1 occurrencelibproxy.smith.edu; in total 2 occurrenceslibezproxy2.syr.edu; only 1 occurrencelib-ezproxy.tamu.edu; only 1 occurrenceezproxy.tcu.edu; only 1 occurrenceproxy.uchicago.edu; only 1 occurrenceproxy-remote.galib.uga.edu; in total 5 occurrencesproxy.lib.umich.edu; in total 5 occurrencesezproxy.lib.utexas.edu; so far 3 occurrenceslibproxy.wustl.edu; in total 3 occurrencesezproxy.weizmann.ac.il; only 1 occurrenceezlibproxy1.ntu.edu.sg; in total 3 occurrencesproxy.ub.umu.se; only 1 occurrenceezproxy.is.ed.ac.uk; only 1 occurrenceezproxy.webfeat.lib.ed.ac.uk; 2 occurrences
Typically the rewrite would look like this:
- http://www.ams.org.proxy.library.adelaide.edu.au/mathscinet-getitem?mr=46042 $\to$ http://www.ams.org/mathscinet-getitem?mr=46042 (from this answer)
- http://www.numdam.org.proxy.library.cornell.edu/item?id=CM_1983__49_3_405_0 $\to$ http://www.numdam.org/item?id=CM_1983__49_3_405_0 (from this question)
- http://ezproxy.library.nyu.edu:2233/mathscinet-getitem?mr=1042048 $\to$ http://www.ams.org/mathscinet-getitem?mr=1042048 (from this answer)
- http://www.jstor.org.libproxy.smith.edu:2048/stable/2031721 $\to$ http://www.jstor.org/stable/2031721 (from this question)
Some differently looking changes: