I've been watching some youtube videos of people making screens that snap into the van openings. Windows or back door area. I would love to make an attempt at it when I have extra time. I freaking hate mosquitoes.
I have a Thermacell. They use a butane cartridge and a pad of repellent. (allethrin). They work well and keep a circle of mosquito-free-zone. I don't smell anything, but do notice a small amount of smoke sometimes. I use them outdoors, or in the van with all the doors and windows open.
"Citronella torch oil and diesel mixed about 50/50 burning in my kerosene lanterns... Them dang bugs keep a fair distance! (um...so does everyone else but that's another story!)"
In order of effectiveness (from someone who has spent lots of time in Northern Minnesota woods):
Move to someplace without bugs.
Find a windy spot or create wind with fans.
A screened-in enclosure.
Specialized clothing and headset, Permethrin treated or not.
Chemicals that repel (these can be insect specific, so you need to know what insects you are trying to repel).
Smudge pots, area protectants. Citronella torches (best if they surround your campsite).
A good campfire. If bugs aren't too thick most of them are attracted to the fire. Sitting (or sleeping) in the smoke of a fire is very effective and very uncomfortable (and unhealthy).
Grease. The Ojibwa would smear bear grease over their body to get releaf. Never tried it, so I cannot comment on effectiveness. Vasoline would probably work.
For mosquitoes:
DEET is the best, and WebMD says it is safe to 30% solution on any but small children. Will dissolve plastics and nylon.
Pecaridin for those who don't like DEET or are allergic to it. Not as effective as DEET.
Had a girlfriend that claimed Avon Skin-So-Soft bath oil worked. (no personal experience).
Citronella oil. Very strong smell.
Permethrin for clothing (don't use it on skin).
There are other synthetic and natural repellents that I have not tried.
I have used a thermacell with good effectiveness to clear out my camper before bedtime. Placed in the front of the camper with a small fan and open the back door. A little effort to stir up the critters hiding in the corners and other dead air spaces clears the camper very well. Not much interrupts a good sleep as a skeeter buzzing your ear or black flies attacking.
Permethrin concentrate mixed to 3%ish in spray bottle and a $50 13x9 Walmart screen tent. The van doors are pretty much always open(rear and front passenger) in nice weather. Fly's get bothersome sometimes, but then spray down interior of van and take 15 min walk while the insecticide dries and fly's die(or whatever bug). We boondock or camp at cheap places. Prob spend $40-$50 bucks a year on permethrin concentrate a year. Maybe less.
Natural Pyrethrum and synthetic Pyrethrin was once used in Raid Flying Insect spray. It worked very well as a repellent, sprayed over our van when attacked by Canadian hordes of mosquitoes. Today's Raid is different, but I bet someone makes Pyrethrum.
the mosquitoes in my home town leave me alone. but in fla or maine or other places they get me. being bit so much as a child gave me protective something.
Here's an article link on purchasing and applying Martin's 10% Permethrin from Amazon or wherever ($22,32oz) and mixing 19 water / 1 to make a standard solution for treating clothes. Significantly cheaper than ready to use .05 solution (e.g. Sawyer).