Ankle Sprain=8-12 week upper body training opportunity?

I sprained my ankle badly last week and am not sure how best to spend the 2-3 month rehab period w/o bouldering, hard leading or max campusing. Normally now I would be in a power/strength phase bouldering outside and inside w/ some fill-in campus and hangboard. I then add endurance (not too much - I climb at Rumney!) in March/April for the sport season.

Ankle rehab aside - I have that covered- this could be an opportunity to actually get some forearm hypertrophy or maybe just sustained gains on the hangboard or system board. Or someone suggested, uh, rest. But I'm probably not going to do that.

All ideas welcome! - not sure 12 weeks is enough for significant hypertrophy of finger flexors (is that right?) but I have always liked the idea of first growing dumb larger muscles then smartening them up w/ recruitment and more sport specific isometric exercises. Another idea might be to really strengthen the wrist extensors - I've always suspected they play a much bigger stabilizing role in climbing movement than people think.

Climbing has always gotten in the way of my training - until NOW! What should I do, please? (ht 6', 170lb, ape index 0"; PB V7, 13b; age: old)

Thanks!