Tell her no diesel, no fifth wheel.
There's no comparison between towing a fifth wheel vs. a travel trailer, a fifth wheel is much nicer. The only downside is the loss of bed space with the fifth wheel.
Check the pin weight on that fifth wheel you're talking about. I'll bet that the pin weight puts you over the payload of the tundra. Half ton trucks aren't really meant to tow fifth wheels.
I went back and did a little calc on that Tundra and the 5er she's looking at.. Most 5ers have pin weights of about 20% of total weight, therefore you'll have 1280# in the bed before you load it up.. Add 2-3 adults, full fuel tank, gear etc., (not to mention the hitch) and you're overweight. That truck's gonna squat and that means you can bottom out on dips and break things.. Plus, what weight are you licensed for? What's the load rating on your rear axle? What's the axle ratio?
My 5er's pin weight is about 1640# and the EW of the trailer's nearly 8,000#. GVW is 12,500#... My truck's GVW is 11,500# GVW and the rear axle's rated for 9,000# with an axle ratio of 3.73.. And I probably should have 4.10 instead, but I rarely carry to full load - maybe once per year..
If your trailer weighs about 6640# empty, that means max GVW is more likely close to 10,500#.. That's too much trailer for that truck and for sure you're going to have issues with payload.. And yes, while it's flat where you are now, are you going to be camping always in flat areas? When you find hills you'll wish you had a bigger truck.. Plus, there's the issue of braking.. Do you have a good controller? Is your truck an auto or manual trans? If manual, your gears will sure help on downgrades..
If you do nothing else, do NOT listen to the trailer salesman who will tell you that your truck can pull a 33' triple with ease.. Call Toyota and talk to someone who can give you honest answers as to what weight you can carry and how much trailer you can pull...
