You can post one ad in the regular ad section and one in the weekend ad section (Thurs-Sun), so that's two. Theoretically, your weekend ad must be for the weekend, but you can put in your future travels in it as well as where you'll be that weekend. You can also post a thread in the coed section just announcing that you'll be coming to Hattiesburg and hope to have some fun while you're there. That is called a threAD, and while it's not exactly kosher, it's always been allowed. Best,though, is to put all of your travels for the week (or even farther ahead in time) in the ads you can post.
Just re-read your post, and I think I need to add some info - the rules say up to 5 ads per week. In a state like Texas, you can post in 5 different cities. Unfortunately, there is only one MS board, so you can only post one ad on the MS board per week (and a second in the weekend lineup). There is no way to post an ad for different cities in Mississippi. So, as I mentioned in my other reply, it's best to plan ahead if possible and put all the cities in the one ad, or you can use a threAD to announce an unexpected visit.
Like JAG said there is only one MS forum, though more might be added in the future! That mean 1 ad in the Provider Ad forum every 7 days and 1 ad in the Weekend Ad forum each week (only posted between Thu 6am - Sun 9pm). Of course that's in addition to 4 other Provider Ad & Weekend Ad in other cities each week, like New Orleans, Mobile, Pensacola, etc. An example of how to maximize your ads would be:
On every Monday - place your Provider Ad for MS listing where you are available. For instance, if you're willing to travel your ad might read like this:
Biloxi/Gulfport - May 13-14
Hattiesburg - May 15
Jackson - May 16-17
On Thursday place your Weekend Ad to let guys know where you're available over the weekend.
Available May 17-19 in Hattiesburg
May 24-26 in Jackson
The more notice the better in terms of giving guys time to schedule and if you post cities/dates that later change, just PM one of the local Moderators and they can edit your ad if it's too soon to place another ad.