The frontier idea is a solid one. They are good trucks that don't usually carry the Toyota tax. I did look at a few when I was shopping, but in all cases they had hardcore rust issues. It's not so much a frame/body rust, but it seems like all the hoses and engine parts rust; PS lines, cooler lines, radiator supports, hood hinges, etc.
I'll look again, but I recall finding several Frontiers that were very much not worth what they were bringing compared to other trucks.
Tacos are great trucks, but they fall into the "factor of two" category. If you compare a Taco to any other compact truck with the same specs, it will sell for twice as much. Conversely, if you find a Taco and another truck for the same price, the Taco has twice the mileage. Great trucks, but in order to get one for $8000, it will be a wasted rust pile compared to a same-price Ranger, S10, F150, etc.
Also, for the sake of this discussion, it might be helpful for all of you to know that I detest high-mileage vehicles. I would rather have an older truck with low miles than a newer one with high miles. Miles = wear. There's kinda no way around that. I understand that some vehicles (like Tacos) last longer, but it's more than just how long the engine will last.
I don't mind considering a full size truck. My last two trucks were F150s, but I really don't want the size. This Branger has done all I've asked of it (when it runs).
I would consider a mid-sized, except that limits me to Dakota (pass) and later Colorado/Canyon... which, in case you hadn't noticed, are nearly as big as a GMT400. Hard to find a Colo/Canyon that is under $20k right now.