99% of the time, trusts that pay a dividend this large do no make their shares avail to any brokerage to short. However, I have been shorting calls prior to ex-dividend date and making a killing. Every quarter, the stock drops more than the dividend pay-out. If you just try to do a "dividend capture" you've been losing more on the stock than you've received in dividends.
you 'should be' but will usually find when you try to do it that there are no units available to borrow.
plus it is risky, even if you are right about the valuation, for reasons I explained elsewhere (people who shorted at $5 weeks ago) may have been forced to cover in the $7's this week if the borrowed unit were sold by the owner taking profits.