Yogi Welcome to the Forum!
First, you are fine towing a 8,000# TT with your F150 since you are the only passenger. Your F150 will be carrying you (150#?), 80# WD hitch, 100# misc stuff and 800# hitch wt = 1050# - certainly well below your max payload.
I hate to say it, but your current setup may well be the best for your family.
To evaluate a new tow vehicle, DO NOT look at published Max Tow Capacity. It does not include any passengers past a driver and one passenger @ 150# each.
Add up the weight of all family members (5 year from now weights?), all car seats, kid entertainment, snacks, diaper bags, tools and anything else carried in the vehicle. Add 80# for a WD hitch. Add 800# hitch weight for the TT. The PAYLOAD of the vehicle must exceed this number.
A word on Payload: Published payloads assume a base vehicle with few options. The real payload is found on the driver door latch post on a yellow label. It states the weight of all occupants and cargo shall not exceed XXXX. That number is for THAT vehicle as it left the factory. Use that number ONLY!