Gaining

Staying between the extremes you could probably look to gain 8 lbs a week since you gain easily. Saying between the extremes I mean that I have known women who gained 8 lbs in a three day weekend. I have also known even more who would struggle to gain even 15 lbs in the entire 6 weeks. Since you gain easily and probably have a good capacity at 260? Or are you 245? Regardless you surely can take in a nice amount of calories.
If you eat heartily and add in several cake shakes every week you could easily gain 50+ lbs and welcome him back as a 300+ lbs Goddess.He will be like someone ina wweight gain fiction story except it will be real life.

If you really want to push how much you gain, I agree that advance planning will help.

First of all, know your budget! A week of feasting followed by five weeks of bread and water because you are broke won't help, lol.

Second, steady eating all day will let you eat more than just stuffing yourself at night. So figure out how to make the most of whatever snacking and meals you can do at work, school, etc. Can you bring biscuits with you, or some extra fruit, after you regular lunch is there time to step out for a high calorie treat, etc. How will you remember to eat every hour or two?

Third, how do keep up variety, and make it fun, so it rodent become a chore? Varying food helps, but maybe you could also set yourself challenges or mini goals?

Fourth, what about clothes? If you do well, do you enough clothes with enough space in them to avoid being painfully squeezed?

I think that if you work through that planning, you won't have trouble packing on a good amount

Doh! The perils of posting from my phone, with autocorrect on! Should have been "wouldn't"