To sweeten the deal, I will place no contingencies in the contract and agree to close ASAP.

Ideally, you make an offer without an option period to sweeten the pot. 

Is it legal for me to sweeten the deal for the seller's agent?

Sure, you might find a deal which looks promising, and if your offer is not accepted the first time, you'll feel a tinge of disappointment.Re-focus: get back to the numbers and see if you can "sweeten the deal" for the seller.

If the powers that be don't deem you worthy of cross selling, then you will just get the same deal that every other Joe off the street gets, they might however sweeten the pot a little bit if you agree to move your checking/savings account business to them.This all goes back to what Wells Fargo got in trouble for not too long ago: "Each customer should have eight accounts with us." 2nd mortgages are basically the free sample of crack to get you visiting their street corner.

Sweeten the deal if you can make the offer more appealing.

When you start to get into $1.6+ million, that's where non-recourse, institutional financing comes into play which sweetens the pot considerably compared to the traditional 20-year, floating rate commercial loan on a $1.5 million property.Another thought: 25 units sounds like a lot, but it's not enough to hire out full time management and maintenance. 

Or if they’re willing to owner finance it and then travel then $2k per month might work for them, maybe sweeten the deal with they have rights to a free RV hook up when they’re in GA.

If it's a good deal try another angle to sweeten the deal (usually price).

These are the most used sweeteners in our vacation house, but 1000 packets lasts a long time.https://www.amazon.com/Splenda...If you want to add a fun little small appliance to your vacation home.