Does your 3800 have a two piece locker cover over a very shallow space? On mine the forward triangular shaped foot or more is screwed down. Then behind that is a raised hinged hatch over the anchor winch. Below all this is a chain locker with a door into the vee-berth. The original owner cut out the bottom of the chain locker to allow the chain to fall deeper into the boat. The chain now rests against the forward water tank deep in the bow.
My 3800 has a horizontal axis anchor winch. The lid for the anchor winch locker is raised with a slot in the front to allow the chain to pass from the anchor to the winch. Is your anchor winch locker hatch flat or raised?
If it is raised, then you would mount a horizontal axis winch on a reinforcing platform under the raised part of the hatch. The winch model would need to be low enough to fit under the raised hatch.
If the hatch lid is flat, you could perhaps cut the hatch from side to side half way back, reinforce the portion where you want the winch, bolt it down to the deck, and then mount the winch on top. The remining portion of the hatch would need a new hinge arrangement.
A flat hatch lid could be cut and modified to have a raised portion to allow a winch to be mounted below it.
All these situations require considerable work. Then the winch requires heavy power cables. Some boats install a battery near the winch, and then run smaller power cables to charge the battery. If the power comes directly from the house battery bank without the nearby battery, the cables have to be really beefy. On my 3800 these cables are run through recesses in the floor pan / grid between the center line table and the Port water tank. The floor boards are bunged down so to access the space the bungs have to be removed, and the floor boards lifted. I wanted access to this area, so when I did it, I reinstalled the floor boards with visible stainless screws - making the boards easy to remove in the future, but not looking quite as pretty.
Other boats, and newer Tartan designs have anchor wells that are drained overboard, and sealed off from the rest of the boat. I have thought about doing this, but obviously it is a lot of work. The advantage would be keeping salt water and smell out of the boat. On the Strait of Georgia I've had the boat pound into some big waves, where water went down the chain opening below the winch into the anchor locker, and then spray through the louvered door onto the Vee-berth cushions. I need to remember to tape up a piece of plastic over the louvers on days there might be water over the deck.