Yes, there are multiple flights from Bangkok to Gulfport for under ฿ 41,923. The cheapest flight booked recently is on American Airlines for just ฿ 39,737, but on average you can expect to pay ฿ 43,360.
There are no direct flights from Bangkok to Gulfport, but Cheapflights can provide you with all the information you need to find the fastest route with the fewest stops.
You can imagine temperatures to be in the 36 °C range in April. The weather in Gulfport is generally colder than Bangkok's. As flight availability is subject to become more limited as peak season approaches it is ideal to book in a timely manner.
There are many flights that can get you from Bangkok to Gulfport in 26h 17m. Fly via American Airlines or Qatar Airways to get the fastest option. Both multi-stop and direct flights can be found to your destination and back.
Flying on American Airlines is currently your cheapest option to Gulfport, with prices starting at ฿ 39,737. Another option worth looking into is Qatar Airways, starting at ฿ 50,607 return.