Kind of curious about the remarks in regards to measuring tank level?
Level in a multi-chambered tank has nothing to do with needing to be pumped. Most modern tanks are a 2-3 chambered system where each section has to fill up and spill over to the next. As long as the the last section isn't full beyond the outflow, all is typically well in terms of system functionality. Each chamber will have it's own lid that ideally should be dug-up and removed for pumping, but the first chamber will contain most of the solids- or it should atleast.
Like Pops said, more modern systems built in the last 30yrs or so will have a Zaebo filter (outflow filter) to take out particulate matter before the gray water flows into your absorbtion field. The filter can be in the last chamber of your tank, in it's own chamber or in your distribution box. These should be hosed off when the system is being pumped.
Also, like said, guests are going to flush tampons and whatnot. Totally gross stringy mess that just sits there. Soft, fluffy toilet paper is another issue. I've seen tanks in the aftermath of fluffy toilet paper use. A solid mass of paper pulp. Stick with simple single ply paper and go as easy on it as possible. Waxes and oils build-up over time as well, and you don't want those going into your absorbtion field.
In my area, a 1000g tank pumping is about $200. When I had to have a brand-new 1500g sand filter system put in our last home because it wouldn't pass inspection for sale, it cost me $8500. About $10K is typical now in my area for a 1500g sand filter system.