If you are not afraid of or opposed to chemicals read on, if you are, stop here and find another thread to read.
Working for the health department, we try to curtail the mosquito population. I know, what's mosquito control have to do with ants? Give me time, I'll get around to it. We use a product from Durvet that has 10% Permethrin, here's a link to the website: http://www.durvet.com/index.php?option=com_k2&view=item&id=92:permethrin-10&Itemid=64
This is a fairly safe product when used as directed. I / we use it around home to control flying pests as well as a barrier spray around the house.(wall of defense) It sells for less than $10 a quart usually, and this qt will make up to 25 gal of product. We mix it at only 3 oz per gallon.(has an easy to use 1.5 oz measure built into the container)
This product is even safe to use on your pets! Horsey people should be familiar with it. Control of ants is on the label also! (I told you I would get around to it)
My thought is, mix it up to use in a small spray bottle (old window cleaner spray bottle or something - BE SURE To Re-label as to the contents!), when you set up your camp, spray a ring on the ground around your tires / stabilizer jacks / tongue jack / etc. This should keep any of the creepy crawly's from climbing up into your camper (even scorpions is listed) If you are boondocking and are going to be in one place for a while, spray the folage around your camp site to control mosquitoes, flys, etc (if spraying is permitted of course)
This chemical is low odor, dries clear (leave no trace), non-corrosive, and in general is a good all around pest control. It will last up to like 28 days or the next rain will wash it off.
Disclaimer: Always read and follow instructions on the label. (just had to do it)
I hope this don't sound like an advertisement for them, this is just a good all around product for pest control.