Complex custom post type multiple loops in WordPress

I have a custom post type for Staff Members of an organisation with a taxonomy named Profession. I’m using easytabs to display a matrix of photos for each member sorted into different professions (taxonomys). When a user clicks on the photo (the tab navigation), the appropriate information is displayed in the panel as it animates to view.

I can only fit 4 members in each tab container div across the page, any more and the 5th one breaks the tab layout.

The way easytabs is structured, I need firstly a <ul> of nav items then followed by the corresponding tab panels. I have achieved this by using rewind_posts().

I need a loop to pull only 4 Staff Members per tab-container div (see code below), then create a new tab container the next 4 etc.

This is the code I have so far …

<div class="team_content">
				<?php
					$custom_terms = get_terms('profession');

					foreach($custom_terms as $custom_term) {
						wp_reset_query();
						    $args = array('post_type' => 'team_members',
						        'tax_query' => array(
						            array(
						                'taxonomy' => 'profession',
						                'field' => 'slug',
						                'terms' => $custom_term->slug,
						            ),
						        ),
						     );

						     $loop = new WP_Query($args);
						     if($loop->have_posts()) {
						        echo '<h2>'.$custom_term->name.'</h2>'; //displays the profession

						        echo '<div class="tab-container">';
	 								echo '<ul>';

						        while($loop->have_posts()) : $loop->the_post(); //first sub-loop sets up the nav <ul>

						        	//extract field names from metaboxes
							        $salutation = get_post_meta( $post->ID, '_cmb_salutation', true );
							        $full_title = $salutation.' '.get_the_title(); // create entire title eg Dr. John Smith
							        $title = get_the_title();
							        $title_link = str_replace(' ','',$title); // remove spaces to make links work
							        $final_title_link = strtolower($title_link);

							        echo '<li><a href="#'.$final_title_link.'">';
							        the_post_thumbnail("team-member");
							        echo '<h4>'.$full_title.'</h4></a></li>';

								endwhile;

									echo '</ul>';

								rewind_posts();

								echo '<div class="panel-container">';

								while($loop->have_posts()) : $loop->the_post(); //second sub-loop sets up the tab panels

						        	//extract field names from metaboxes
									$profession = get_post_meta( $post->ID, '_cmb_profession', true );
									$qualifications = get_post_meta( $post->ID, '_cmb_qualifications', true );
									$services_url = get_post_meta( $post->ID, '_cmb_services_url', true );
									$title2 = get_the_title(); //this variable must be re-created for this sub loop
							        $title_link2 = str_replace(' ','',$title2); //this variable must be re-created for this sub loop
							        $final_title_link2 = strtolower($title_link2); //this variable must be re-created for this sub loop

									echo '<div id="'.$final_title_link2.'" class="member_info">';
										echo '<h4>'.$profession.' '.$qualifications.'</h4>';
										the_content();
										echo '<a href="'.$services_url.'" class="button2">Visit Service Page</a>'; //Services page link
									echo '</div>';

								endwhile;

								echo '</div>'; //panel-container

								}

							echo '</div>'; //tab-container

							}
						?>

			</div><!-- .team_content -->