Fort to the end

OK, let’s see what we’re facing...

Our target is a well built rectangular wooden fort. I’m guessing it’s about one hundred feet along the longest sides and maybe sixty feet at its most narrow?
It’s surrounded by a ten foot patrolled palisade and it seems there is a construction inside the wall since the guards can be seen over the palisade..
The palisade has two gates in the centres of the two shortest walls on opposite sides of the fort. These gates are fortified and have small guard towers on either side.
Do we know how tall these towers are?
The sturdy wooden gates open outward.
There are eight buildings inside.
The one near the north gate seems to be the troop's quarters. They are in two lines along the road in between the gates.
There are at least ten regular guards, but that’s including their commander and an accursed black cloak.
The road passes in the west while there is forest on the other sides.
There's about a fifty foot distance from the palisade to the forest's edge.
Carts normally seem to enter at one gate and leave through the other after being loaded or unloaded by the people that are with the cart and just supervised by a guard.

There also appears to be a kind of quick response group stationed there to protect the roads near the fort. Ten mounted fighters who control the roads and pass the fort on two regular passes throughout the day and stay there over night.
Annoyingly these cavalrymen don’t were helmets and are well known and easily recogniseable by the men in the garrison.

The fort act as an intermediate storage facility. The are carts bringing and taking stuff. They mostly supply troops that are passing through and get re-stocked when necessary.
The fort is simple though. A wooden construction and no moat or slope to worry about.

I still think fire’s our best option. If we could get Indigo in somehow, he could stealthily poor oil on the thatched roofs . In fact he could set the fires AND help open the gate..
Then it would be a simple matter for archers shooting fire-arrows into the fort to light the place up.
Wooden fortifications are always susceptible to fire. A few buckets of water and damp leather are no match for burning oil and bloody mindedness.
As the fire spreads, those living inside would be forced to flee, thereby allowing us to take them prisoner or kill them.

Our main problem though is still the matter of getting in...
Do any of us have any abilities that would help?

As for the problem of not destroying what we’ve come here to get. We don’t have to target every building. The guard house and one or two others would do.
I’ve thought about what Orestes had said about their fire defences. They are very unlikely to be keeping the wood damp as that would lead to it rotting.
And regardless of that, it would distract at least a few of them.
Interestingly, as the garrison is so lightly defended, there should only be six or so defenders initially as at least a third of them will be asleep preparing for or recovering from the night shift.

I also think we all now agree that it’s best for us to strike fast during the day, between the cavalry passes and be gone before they return. Killing them can wait for another day.

Of our assets, we have the five of us and the possible support of about 15 untrained men and women. Frankly I’d rather we left them behind to protect their settlement.

We don’t have any belfries, battering rams or catapults and using ladders would prove disasterous. Mining’s out as we don’t have any Dwarves and we haven’t got time for a siege

So unless anyone can offer a better suggestion?