Jesus, it doesn't seem that outrageous of a setup...

Seems what would fit nicely is to host a copy of privoxy (and maybe even Tor) on one of your local machines. Set it up to be available to all machines on your 169.254 subnet and set the 770 to proxy through it. Wahla, adblock (and even anonymity) without extra cpu cycles on the tablet

..although you'd probably need a separate proxy for voip / chat etc. Maybe it is a little whacked