Most advice says to decide on fifth wheel first, then buy the truck to pull it--many have done it the other way, only to find themselves limited to towing less than they wanted.
Remember, if looking at NEW units, the 'dry weights'/'ship weights' are invariably very optimistically LIGHT. And if a salesman's lips are moving, he is probably embellishing the truth--would be rare to get a caring, knowledgeable sales person.
In looking at any fiver, take the gross weight rating (GVWR) and multiply it by .2--that will be very near the pin weight of the fiver when loaded for travel/living. Then, you have the estimate of the weight you will place on the rear axle of the tow vehicle.
Living in it? Can be very claustrophobic if used to a large home--the floorplan needs to be very livable for your wife--and you, of course. Washer/dryer? 2ACs--absolute necessity in TX, maybe 3 if you end up with one of the 43-45ft fivers.
Good online places to look at fivers: RVTrader.com ; pplmotorhomes.com ; rvt.com
start a good notebook when you find a unit you feel good about--its kind of like looking at houses--no notes/pics, things get blurry.
Have fun in the search...
2016 Tiffin 40 QBH
2015 38RSSA, traded
2005 TK3 #1869, 10 yrs of memories,
2017 F450 KR--one more Ford is it
2009 F450 4x4-died; 2010 F450-retired