No, restaurant campers are not people who pitch a tent in the middle of a restaurant. Rather, in the restaurant industry, ‘campers' are customers who stay at a table for a long time, longer than average. Some operators believe that a long stay results in a larger check, so they have no problem with campers.
Upserve's January 2018 State of the Restaurant Industry Report found that those foodservice operators are indeed correct. The longer the stay, the higher the check.
However, while the average check grew to $123 at 80 minutes and jumped to $180 at 100 minutes, the amount of revenue per minute drops from $2.08 per minute to $1.54 per minute from the 40- to the 80-minute mark.
The data showed little benefit from lingering guests on a revenue per minute basis.
Upserve's data also showed that the tips increased with time spent at the table up until about the 40-50 minute mark. However, as time progresses, although the total tip size continues to grow, the tip as a percentage of check decreases, possibly indicating price-shocked parties or the greater use of automatic gratuities. So while the tip is highest at 110 minutes, it's a much smaller percentage of the final bill.
The Upserve's research indicates that aiming for a 45-minute table turnover maximizes restaurant revenues and servers' tips. This of course assumes there are other customers waiting be seated at the the table. Otherwise, letting diners linger will be the best strategy.