All cash purchase, taking out a mortgage post closing

My husband and I closed on our co op one week ago. We purchased the unit in cash (had to clear out almost all of our investment accounts) and now our financial advisor has floated the idea of taking out a mortgage post closing, so we can resume investing and hopefully make enough to cover mortgage payments and then some.

My husband is very nervous that this would upset the board since we were approved for an all cash offer, so my question is how would they know? And would they care if for some reason they found out?

I should mention that we had to put one year of maintenance fees in escrow for two years as part of the sale, and in two years we can petition the board to get it back. At that point they would see updated financials and I assume they would find out then if we did take out this mortgage, and it wouldn’t necessarily help our case…

We’re not sure we are going through with this regardless of the board, just want to invest all possibilities here.