Current sleeper mechanics aren't bad, but they make sleepers a rather distant part of the active LCS, with very little interaction between the two. I suggest that in addition to having a personal infiltration%, each site would have its own infiltration%, representing the overall success of liberals compromising the site without making the conservatives suspicious. Having a high site infiltration would provide bonuses for raiding liberals, while the personal infiltration would, like it does now, aid the sleeper in embezzlement etc, as well as providing powerful one-shot effects in exchange for site infiltration.
Site infiltration be initialized at 0% and will rise very slowly if one has sleepers on the site, but inifiltration can be accelerated to 3-5% a month by having multiple sleepers actively survey the site. Site raiding slows the increase, maybe even decreasing infiltration if done frequently enough. Possible effects for site infiltration, just a draft:
Any sleeper on site: Sitemap without specials and loot
5%: Front door unlocked
10%: Loot placed on sitemap
20%: Specials placed on sitemap
30%: Exaggeration: Raid effects increased
40%: All doors unlocked
50%: Sensible excuses: Disguises receive a slight boost
60%: Can start fire in exchange of 10% site infiltration, fire will be created in 1-3 random rooms in the beginning of the next raid targeting the site
70%: Can relax security on site in exchange of 15% site infiltration, less armed and suspicious conservatives during the next raid
80%: Blatant exaggeration: Raid effects increased further
90%: Site evacuation takes longer to kick in, all normal sleeper activities boosted
100%: SITE TAKEOVER! The sleepers will prepare a takeover operation, which will be carried out by the next squad raiding the site. From this point forward, the site is a special safehouse, and will remain one until there is no one there to defend it. As long as you control the site, political damage related to the site is dealt to the conservatives. The site will be left destroyed when the takeover squad leaves, and it will take a few weeks for the conservatives to reopen it. The takeover will assure the conservatives that there were sleepers in the facility, so you'll lose almost all site infiltration on that site.