I agree with your idea, Northern. Do both mosquitoes and perimeter around the house at the same trip with the backpack mist blower. Lots of houses have heavy plantings around the house that harbor tons of mosquitoes. Charge the customer for both--and then--give them $20 off, as you save a trip. And the backpack mist blower is probably sufficient for most ticks and surface insects in the turf, also. Naturally, you want to put plenty of air pressure into the turf to drive the chemical down deep into the grass. OK if you walk the lawn with a swath width of six feet and aim the nozzle mostly down. If your blower produces a wind of about 100 mph--it should get the chemical deep into the grass--at least as good as water-based solutions.
Of course, you will have to find a chemical or combination that is suitable for all the different kinds of insect pests that need control, (and maybe a few spiders).