Common issue with retracts and rough fields is ripping them out of the wing. HOW you do the beef up matters.
You also need to do something to absorb the impacts rather than just transferring to the structure.
there are many approaches but I tend to aim for keeping things as light as practical.
If the retract mount is just supported on some balsa ribs then double the ribs with thin aircraft ply 1/32 or 1/64. and add some 1/4 inch triangle stock to beef up the joints.
In some cases I just punt and use a spray foam to fill the wing bay the retract mount is in. Then when it cures, carve out the excess foam so I can put the retract back in.
To reduce stress on the wing use the largest dia tire you can get away with and use a softer wire strut. Its easier to straighten struts than to rebuild a wing.
If the tire is hard it will transfer all of the impact tot he axle... softer foam can help in many cases.
If you have spring loaded "oleo" struts
(or similar) they often have the spring too strong to compress before the wing breaks. You want the weight of the aircraft to slightly compress the strut when the plane is sitting still. I commonly cut one to 5 turns of the spring off.
Depending on the situation... some or all of these might help.