Hmm... 1- BPs don't 'bask' per say, they stay in one hide or the other depending on their temp desires.
2- I wouldn't go lower then 90 for the warm side temps. 80's are for the cool side.

As for 'sideways' I assume you mean long instead of deep. Well, that's how I built mine:



Saves space IMO and is easier to maintain a gradient. Also lets you see more . For heating, I used UTHs - 30gal size for warm sides for better coverage and 10gal size for cool sides. That's just how I do it, tho.