I have heard gophers love figs, so they might not bother the pear as much. I would use chicken wire, I would fear the small holes on the hardware cloth will restrict growth too much. Chicken wire degrades in a few years, but the tree will be large enough to withstand attacks by then.

I had good luck using poison grain placed in the burrow with the tool designed for that purpose. Haven't tried the cages because I always had so many trees. If I were going to try wire, I'd use the 1/2 inch galvanied hardware cloth and make the cage as large as possible. I really don't think this would seriously hurt the roots. I've had plants in pots root thru AL window screen. That never seemed to slow down the roots. I think they'll just heal around the wire. At most it might dwarf the tree a little, not usually a bad thing.

The Fruitnut

Figs are very attractive to gophers. Pears seam to be down the list a bit. I had gophers take out a cherry and a fig. Getting several good cats seemed to slowed the gophers down a bit. I use 48" x 1/2" avian wire netting to make 48" diameter cages. I think the netting will corrode away in 5-10 years after the tree is established. I haven't found any other controls for gophers that work consistently. Commercial growers blast them out with propane, and poison them with restricted poisons that require a permit.

To make a cage, I start with a 13' length of netting and slit 6" up every 16". Bend up the slit portion to make tabs along the length of the netting. Secure the ends together by "stitching" them with a 48" length of stiff wire (probably wouldn't work with hardware cloth). Fill in the bottom of the cage with a separate piece of netting overlapping the tabs.