Question: I've just started editing my novel. 

For the drafting I had done most of the work on a phone, as I wanted to make the most of the daily commute. This worked well enough and the first rough draft is done. 

However, I'm finding the same approach just isn't as strong for editing as it's not easy to highlight and remove words or find things quickly on a phone. 

Does a portable computer exist that would be up to the task? A tiny laptop could work but I currently commute by bus (not train) so there isn't exactly a table or other surface I could rest a computer on. 

My other option is just working weekends, but I'd rather avoid this if possible. 

Can any writers recommend any suitable tools?

If not, how did you keep productive during the editing stage?

Answer: 
For the hardware aspect of the question, you may try a tablet. So you'll get a wider surface to edit your text, without the need of a table. Mouse and keyboard will still missing, but at least, editing should be easier. But you may prefer a tiny laptop on your knees.

For the software part, I suggest [LiteWrite](https://litewrite.net). Beautiful on desktop as well as on phone, tiny, no distraction, data ubiquity, it let you choose your cloud provider (GoogledDrive, DropBox or [RemoteStorage](https://remotestorage.io)). For a long work, I recommend you to split your text in many documents with a clever naming convention, so you could rely on the search ability of LiteWrite to quickly switch between parts.

If no solution suits you, remember you can always use pen and paper, and type your work at home. Print your draft, edit it with pen on the go. Well, it may not be more comfortable. A [clipboard folder](https://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Doffice-products&field-keywords=Clipboard%20folder) on your knees may help.
To add to what others have said: 

If you choose a tablet:
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* the touchscreen keyboard will be much less ergonomic compared to a real laptop. If you are the kind of person who may be discouraging by that, you can get a wired or Bluetooth portable keyboard.
* a tablet + accessories setup will be more fiddly than a laptop. With a laptop, you will only have one device that you will have to remember to carry and keep charged. With a tablet and keyboard, you will have to keep two charged, and connect/disconnect them occasionally.

If you choose a laptop:
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* they are more tempting to leave behind unattended because of their weight, "just this once, for only a minute". That can get them stolen more easily than with a tablet, which you can train yourself to pick up whenever you leave the room.