need more details, what kind of boat? what kind of toilet?

Smell: what chemicals are you using?

• chemicals: I have a dometic portable (976) and I use TST which you can get at walmart. it gets emptied and more TST put in about weekly. I also keep a sanitizing/de-odorizing spray for after each use.

• maintenance: Every 90 days, ill empty it,then fill it with a mix of water and white vinegar, let it soak for some hours, or ideally overnight. Then bring it to the bath house for a piping hot rinse. This loosens scale that comes off in big chips and flakes. I dump that in the bath house toilet and flush. Removing the scale periodically can help.

• air filter: i got a HEPA air filter, which stays on 100% of the time, next to the portable. Filter is changed every 90 days.

• air freshener pods. For good measure, buy a couple of those egg shape things that you twist open and it has a gel core inside that slowly releases a scent. Place them strategically.

• good venitation. A porthole that opens, or a dorade or something can go a long way. Smells have to go somewhere to be removed, ideally outdoors. Having a fan to help blow out the odor is a big help, and is very effective.

Lack of privacy:

A previous owner of my Pearson 26 removed the stock bulkheads, and added in new custom ones, which had huge horizontal arches cut into it, which sucked (no privacy) i just bought some cheap corrugated plastic (the stuff political signs and the like are made of) and cut it to overlap and tension fit, making a more solid temporary bulkhead. Ill make a more permanent version later out of a shower wall kit.

On my boat, the v-berth, head, saloon are all kind of connected. The head is kind of in its own cubby, but theres no door. I did hang a nice tapestry/curtain where the original door was, so my head is now reasonably private. Its still open to the vberth, but that had sliding wood doors, which ill add back eventually.

• paper:

This is simple, just bring toilet roll on board. If there is a shower in the head, you can buy a waterproof cover/holder. get a small bathroom trash bin from a dollar store, ideally one with a closing/sealing lid, put a sign that says this is where paper and other products go, and only human waste gets flushed.

This wasnt mentioned, but ill add it anyways...

• hand sanitation:

Imo, a good solution is get the wall mounted hand sanitizer dispensers like you see in offices, hospitals, gas stations, etc. These are easy to refill and take up less space. However, i would ALSO make sure there is a sink, running water, and bar soap, and paper or cloth towels for hand drying.

Extra Credit:

If you really want to show you made an effort, add some other basic amenities if they are missing.

• mirror. Girls like to check their hair or makeup.

• a good light (they need to see themselves clearly in the mirror)

• 120v service. This could be an inverter wired to the 12v system, or a powerstation that has household outlets on it. if they are going to overnight especially, they may want to be able to use a curling iron or blow dryer, or whatever other bathroom gadgets. I prefer the power station, because then these gadgets cant suck the capacity out of the house to a point navigation instruments dont work.

• if there is a shower, make sure there are fresh, fluffy, new bath towels.

• have some storage available for personal items. shelf with some empty tupperware tubbies, some drawers, etc.