30's going to be pretty small. I was looking at a 15W panel last year (Cheap solar worth it?
) and when I got all the information from various threads on this site, worked out to barely providing enough juice to compensate for the Co2 detector. Now, this is based on southwestern Ontario, which doesn't get anywhere near as much sun as Texas, but I can't really see a 30W being able to keep up with all the loads in a trailer.
First things first would be to get a real idea of what your actual loads are. Grab a meter, shut things off you won't normally have on and then start measuring. Next, figure out how long you'll be running whatever at those loads. Since you'll be using the genny when you are there, you'll only have to concern yourself with the parasite loads, which will run 24hrs a day. So, let's say radio is .5, CO2 is .5 and fridge is 1 (numbers made up) then you'll be around 2A x 24 hrs = 48Ah you need to replenish in the battery every day. You'll need enough panel for that.
So what's the right size panel? That all depends on several factors, the most important of which is the amount of sunlight. Somebody once provided me with a link to a site that I used to determine this for my area. I can't find that link so a quick google search turned up:
U.S. Solar Radiation Resource Maps
Which seems similar enough (might even be the same site).
In this case, since you'll be leaving doing a leave-it and forget-it setup, you'll need to look at one of the non-tracking options. I don't think it matters much which one in particular, as long as you set up your panels the same way. I had used flat horizontal for mine, since I was thinking of installing it on the roof of my TT.
Using that and a series of calculations that I don't all remember since it was done last year, I found around here I needed 40W of panel for a flat mounted panel to compensate every 1A of parasitic load I had. Unfortunately I don't remember exactly what went into that calculation. (I found where I posted some of it here:
100 watt solar panel?
Assuming I did do my calculations right though, since Texas seems to only receive moderately more radiation than here (per the map I referenced above) I'd guess that 30W panel will be producing about the same 1A parasitic replacement my 40W calculations showed. (Edit: If also flat mounted like I planed)
Of course you'll need to run your own calculations, but hopefully the information in the threads I linked, and subsequent threads they link, and then the subsequent threads they link will arm you to be able to figure this all out.
Please, let us know how it goes.