They believe 'honest hearted ones' will find them. It sounds like predestination to me. But why bother with the preaching work when, if this was true, someone could simply stumble across their website or walk into a KH.
All they need to do is wear an open back pack with a JW org sign and 'Please take a brochure or ask me for a bible study' and they would get plenty of time to record. If they were working, they could include all that time. Their employer might not like it but if it was part of their worship they could probably get away with it. Going to college wouldn't be a problem since it would all be witnessing time. Even spending time shopping could be included. Even going on holidays could become a golden oportunity to witness, that cruise could prov to be very fruitful.
There would be a double benefit. It would encourage the JW to be on his best behaviour, knowing that with his sign, he would always be representing the organization. He's going to think twice before he flirts with someone other than his spouse or any other bad behaviours. That little back pack will be a constant reminder.
They would really stand out in public, a bright orange colour might be the go. It doesn't have to b a back pack, it could be some modified head gear or a shoulder bag, even a wide tie.