We installed a Swift FWC on a friends Gen I Tacoma, they had a double cab with a 5ft bed. Two issues that have to be dealt with. The first is the set up requires external tie downs, which we don't like so we directly bolted the camper to the bed. Not an issue just something to think about.
The second issue was the rear suspension. Toyota made a limited number of the double cabs so there isn't much out there as far as replacement rear springs go. At least nothing that provides a good ride with the camper on and off the vehicle.
We installed airbags on the Tacoma which initially worked well, but then the original leaf springs gave up and wouldn't carry the additional load. Thinking it was just fatigue due to the age of the vehicle and the amount of miles on it we replaced the springs with after market springs with the same specs. These springs were a little better but still not up to the task.
The solution was to install helper springs to carry the load. Not ideal but for people who don't want the camper on all the time it solved the problem.
If you are going to leave the camper on the vehicle having custom made leaf springs is the answer.