Tough question Byron!
Couple thoughts.....
I know you plan on dry camping lakeside east of the park. Given it's your first time to the area I would reconsider that option and camp IN the park at a developed site like Camp Area B w/ electric. Being off pavement in weather, especially not being familiar with the area, could be trouble in the making depending on how much rain that area has already received & the current forecast. If you decide to go & stay in the park it'll give you a chance, weather permitting of course, to explore the area without trailer in tow.
Don't think it's going to happen with this current storm but there's been times the road(s) to Alamo have flooded over cutting off the park from access in or out for a bit.
Although better than it's been in the past, cell service can be spotty to nonexistence depending on where you are at. Some cell carriers service is better than others. Not the place you want to be stuck in the mud at.
And I've heard, not sure how true, that Alamo's Crappie are fair weather fish. Take that for what it's worth, probably nothing but.......
So there's my worst case scenario thoughts. On the other hand, plenty of times the weather forecasters have cried wolf and it ended up being a half way decent day