We don't have any information on the property itself so I'll share a few things:
-Furnished rentals in Tampa Bay are best aligned with short to medium term tenancy. Not to say you cant find a long term tenant but you are fighting an uphill battle.
-As the unit size/room count increases, the pool of those looking for furnished rentals decreases. If it's a larger home, you may end up in a co-living situation.
-Location matters (as always). Proximity to transit/jobs (hospitals/construction/schools)/entertainment (downtown/beaches/restaurants) factor heavily.
Some questions to consider:
Is your property in alignment with the long term rental strategy?
Where are you marketing the property? Is it solely on furnished finder or are you leveraging other sites? Do you have quality pictures and sufficient furniture?
Lastly, in response to your questions:
OOS landlords tend to have a property manager (whether a dedicated PM office or an individual) that work on either a flat fee or % of rents collected. It could be an agent but generally it's a property management company.